diff --git a/bin/configs/kotlin-enum-default-value.yaml b/bin/configs/kotlin-enum-default-value.yaml
index 3d8c9f57a8be..ddb00c552830 100644
--- a/bin/configs/kotlin-enum-default-value.yaml
+++ b/bin/configs/kotlin-enum-default-value.yaml
@@ -6,3 +6,4 @@ additionalProperties:
   artifactId: kotlin-enum-default-value
   serializableModel: "true"
   dateLibrary: java8
+  enumUnknownDefaultCase: true
diff --git a/bin/configs/kotlin-jvm-okhttp3-okhttp3.yaml b/bin/configs/kotlin-jvm-okhttp3-okhttp3.yaml
index f8be34a2f0ac..13baa85c9a64 100644
--- a/bin/configs/kotlin-jvm-okhttp3-okhttp3.yaml
+++ b/bin/configs/kotlin-jvm-okhttp3-okhttp3.yaml
@@ -5,3 +5,4 @@ inputSpec: modules/openapi-generator/src/test/resources/2_0/petstore.yaml
 templateDir: modules/openapi-generator/src/main/resources/kotlin-client
 additionalProperties:
   artifactId: kotlin-petstore-okhttp3
+  enumUnknownDefaultCase: true
diff --git a/bin/configs/swift5-frozenEnums.yaml b/bin/configs/swift5-frozenEnums.yaml
index 64dc04a4f81b..38ca413f3505 100644
--- a/bin/configs/swift5-frozenEnums.yaml
+++ b/bin/configs/swift5-frozenEnums.yaml
@@ -7,6 +7,6 @@ additionalProperties:
   podAuthors: ""
   podSummary: PetstoreClient
   sortParamsByRequiredFlag: false
-  generateFrozenEnums: false
+  enumUnknownDefaultCase: true
   projectName: PetstoreClient
   podHomepage: https://github.com/openapitools/openapi-generator
diff --git a/docs/generators/ada-server.md b/docs/generators/ada-server.md
index 237bb29682bd..f88751432cb6 100644
--- a/docs/generators/ada-server.md
+++ b/docs/generators/ada-server.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |projectName|GNAT project name| |defaultProject|
diff --git a/docs/generators/ada.md b/docs/generators/ada.md
index 06e405243158..3c08371fe24c 100644
--- a/docs/generators/ada.md
+++ b/docs/generators/ada.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |projectName|GNAT project name| |defaultProject|
diff --git a/docs/generators/android.md b/docs/generators/android.md
index f2c6442c6e90..12e99f75cf31 100644
--- a/docs/generators/android.md
+++ b/docs/generators/android.md
@@ -16,6 +16,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|artifact version for use in the generated build.gradle and pom.xml| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |groupId|groupId for use in the generated build.gradle and pom.xml| |null|
 |invokerPackage|root package for generated code| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
diff --git a/docs/generators/apache2.md b/docs/generators/apache2.md
index 8e02718be28b..0db25b032cde 100644
--- a/docs/generators/apache2.md
+++ b/docs/generators/apache2.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
diff --git a/docs/generators/apex.md b/docs/generators/apex.md
index f5179a9d7e9d..89dfd44654d7 100644
--- a/docs/generators/apex.md
+++ b/docs/generators/apex.md
@@ -13,6 +13,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |classPrefix|Prefix for generated classes. Set this to avoid overwriting existing classes in your org.| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |namedCredential|The named credential name for the HTTP callouts| |null|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/asciidoc.md b/docs/generators/asciidoc.md
index 0e309aa541d1..80f949644c80 100644
--- a/docs/generators/asciidoc.md
+++ b/docs/generators/asciidoc.md
@@ -14,6 +14,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |groupId|groupId in generated pom.xml| |null|
 |headerAttributes|generation of asciidoc header meta data attributes (set to false to suppress, default: true)| |true|
 |infoEmail|an email address to contact for inquiries about the application| |null|
diff --git a/docs/generators/avro-schema.md b/docs/generators/avro-schema.md
index 2637a9227433..cbb7dd6e3f07 100644
--- a/docs/generators/avro-schema.md
+++ b/docs/generators/avro-schema.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |packageName|package for generated classes (where supported)| |null|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/bash.md b/docs/generators/bash.md
index a8d3fe169377..590f535c54f5 100644
--- a/docs/generators/bash.md
+++ b/docs/generators/bash.md
@@ -13,6 +13,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |curlOptions|Default cURL options| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |generateBashCompletion|Whether to generate the Bash completion script| |false|
 |generateZshCompletion|Whether to generate the Zsh completion script| |false|
 |hostEnvironmentVariable|Name of environment variable where host can be defined (e.g. PETSTORE_HOST='http://api.openapitools.org:8080')| |null|
diff --git a/docs/generators/c.md b/docs/generators/c.md
index 98f84c458762..c6e5c35372f1 100644
--- a/docs/generators/c.md
+++ b/docs/generators/c.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/clojure.md b/docs/generators/clojure.md
index f5fce29a05bf..cf7b0c3bc03c 100644
--- a/docs/generators/clojure.md
+++ b/docs/generators/clojure.md
@@ -11,6 +11,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |baseNamespace|the base/top namespace (Default: generated from projectName)| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |projectDescription|description of the project (Default: using info.description or &quot;Client library of &lt;projectName&gt;&quot;)| |null|
diff --git a/docs/generators/cpp-qt-client.md b/docs/generators/cpp-qt-client.md
index 96be28abb0af..4bb53da53f33 100644
--- a/docs/generators/cpp-qt-client.md
+++ b/docs/generators/cpp-qt-client.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |cppNamespace|C++ namespace (convention: name::space::for::api).| |OpenAPI|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelNamePrefix|Prefix that will be prepended to all model names.| |OAI|
 |optionalProjectFile|Generate client.pri.| |true|
diff --git a/docs/generators/cpp-qt-qhttpengine-server.md b/docs/generators/cpp-qt-qhttpengine-server.md
index efd57d28d7ad..6126b80c2542 100644
--- a/docs/generators/cpp-qt-qhttpengine-server.md
+++ b/docs/generators/cpp-qt-qhttpengine-server.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |cppNamespace|C++ namespace (convention: name::space::for::api).| |OpenAPI|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelNamePrefix|Prefix that will be prepended to all model names.| |OAI|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/cpp-tiny.md b/docs/generators/cpp-tiny.md
index 1c90b5cbe8e0..4da8351e58a6 100644
--- a/docs/generators/cpp-tiny.md
+++ b/docs/generators/cpp-tiny.md
@@ -11,6 +11,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |controller|name of microcontroller (e.g esp32 or esp8266)| |esp32|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |reservedWordPrefix|Prefix to prepend to reserved words in order to avoid conflicts| |r_|
diff --git a/docs/generators/cpp-tizen.md b/docs/generators/cpp-tizen.md
index c38ec6f5e5c5..7f5b106c048a 100644
--- a/docs/generators/cpp-tizen.md
+++ b/docs/generators/cpp-tizen.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |reservedWordPrefix|Prefix to prepend to reserved words in order to avoid conflicts| |r_|
diff --git a/docs/generators/cpp-ue4.md b/docs/generators/cpp-ue4.md
index b41a208e0e20..be06301a99d8 100644
--- a/docs/generators/cpp-ue4.md
+++ b/docs/generators/cpp-ue4.md
@@ -11,6 +11,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |cppNamespace|C++ namespace (convention: name::space::for::api).| |OpenAPI|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |optionalProjectFile|Generate Build.cs| |true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/crystal.md b/docs/generators/crystal.md
index 93a893215ca4..b79135246bb9 100644
--- a/docs/generators/crystal.md
+++ b/docs/generators/crystal.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/cwiki.md b/docs/generators/cwiki.md
index 0c09a332932b..d10f1d303efc 100644
--- a/docs/generators/cwiki.md
+++ b/docs/generators/cwiki.md
@@ -14,6 +14,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |groupId|groupId in generated pom.xml| |null|
 |infoEmail|an email address to contact for inquiries about the application| |null|
 |infoUrl|a URL where users can get more information about the application| |null|
diff --git a/docs/generators/dart-dio-next.md b/docs/generators/dart-dio-next.md
index d644e35b04a9..869645f7da8f 100644
--- a/docs/generators/dart-dio-next.md
+++ b/docs/generators/dart-dio-next.md
@@ -11,6 +11,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Specify Date library|<dl><dt>**core**</dt><dd>[DEFAULT] Dart core library (DateTime)</dd><dt>**timemachine**</dt><dd>Time Machine is date and time library for Flutter, Web, and Server with support for timezones, calendars, cultures, formatting and parsing.</dd></dl>|core|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |pubAuthor|Author name in generated pubspec| |null|
diff --git a/docs/generators/dart-dio.md b/docs/generators/dart-dio.md
index 9368dc7e7fc5..e3b6ac956394 100644
--- a/docs/generators/dart-dio.md
+++ b/docs/generators/dart-dio.md
@@ -11,6 +11,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**core**</dt><dd>Dart core library (DateTime)</dd><dt>**timemachine**</dt><dd>Time Machine is date and time library for Flutter, Web, and Server with support for timezones, calendars, cultures, formatting and parsing.</dd></dl>|core|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |nullableFields|Make all fields nullable in the JSON payload| |null|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/dart-jaguar.md b/docs/generators/dart-jaguar.md
index 068b5728f02e..769fa166dab3 100644
--- a/docs/generators/dart-jaguar.md
+++ b/docs/generators/dart-jaguar.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |nullableFields|Is the null fields should be in the JSON payload| |null|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/dart.md b/docs/generators/dart.md
index cb783be68109..73f113808b46 100644
--- a/docs/generators/dart.md
+++ b/docs/generators/dart.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |pubAuthor|Author name in generated pubspec| |null|
diff --git a/docs/generators/dynamic-html.md b/docs/generators/dynamic-html.md
index 6c0076fc7fa9..771cecc8b158 100644
--- a/docs/generators/dynamic-html.md
+++ b/docs/generators/dynamic-html.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |groupId|groupId in generated pom.xml| |null|
 |invokerPackage|root package for generated code| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
diff --git a/docs/generators/elixir.md b/docs/generators/elixir.md
index cb8bd35d33a3..543f116ddb25 100644
--- a/docs/generators/elixir.md
+++ b/docs/generators/elixir.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay.Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |licenseHeader|The license header to prepend to the top of all source files.| |null|
diff --git a/docs/generators/fsharp-functions.md b/docs/generators/fsharp-functions.md
index bb16f39fa776..de363c1ca6bb 100644
--- a/docs/generators/fsharp-functions.md
+++ b/docs/generators/fsharp-functions.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |licenseName|The name of the license| |NoLicense|
 |licenseUrl|The URL of the license| |http://localhost|
diff --git a/docs/generators/groovy.md b/docs/generators/groovy.md
index 858464a52e1e..96df596870d7 100644
--- a/docs/generators/groovy.md
+++ b/docs/generators/groovy.md
@@ -24,6 +24,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/haskell-http-client.md b/docs/generators/haskell-http-client.md
index 0e8a66744635..f287982ab71a 100644
--- a/docs/generators/haskell-http-client.md
+++ b/docs/generators/haskell-http-client.md
@@ -21,6 +21,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateTimeParseFormat|overrides the format string used to parse a datetime| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |generateEnums|Generate specific datatypes for OpenAPI enums| |true|
 |generateFormUrlEncodedInstances|Generate FromForm/ToForm instances for models that are used by operations that produce or consume application/x-www-form-urlencoded| |true|
 |generateLenses|Generate Lens optics for Models| |true|
diff --git a/docs/generators/haskell-yesod.md b/docs/generators/haskell-yesod.md
index 415a6f006233..e4f8bd5a3626 100644
--- a/docs/generators/haskell-yesod.md
+++ b/docs/generators/haskell-yesod.md
@@ -11,6 +11,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |apiModuleName|name of the API module (Default: generated from info.title or &quot;API&quot;)| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |projectName|name of the project (Default: generated from info.title or &quot;openapi-haskell-yesod-server&quot;)| |null|
diff --git a/docs/generators/haskell.md b/docs/generators/haskell.md
index 5ce44c462af1..75dfe15ca508 100644
--- a/docs/generators/haskell.md
+++ b/docs/generators/haskell.md
@@ -11,6 +11,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |apiPackage|package for generated api classes| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/html.md b/docs/generators/html.md
index 225daac75448..0ece134692ac 100644
--- a/docs/generators/html.md
+++ b/docs/generators/html.md
@@ -14,6 +14,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |groupId|groupId in generated pom.xml| |null|
 |infoEmail|an email address to contact for inquiries about the application| |null|
 |infoUrl|a URL where users can get more information about the application| |null|
diff --git a/docs/generators/html2.md b/docs/generators/html2.md
index e69d26edf61f..40dc30a42e42 100644
--- a/docs/generators/html2.md
+++ b/docs/generators/html2.md
@@ -14,6 +14,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|artifact version in generated pom.xml. This also becomes part of the generated library's filename| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |groupId|groupId in generated pom.xml| |null|
 |infoEmail|an email address to contact for inquiries about the application| |null|
 |infoUrl|a URL where users can get more information about the application| |null|
diff --git a/docs/generators/java-inflector.md b/docs/generators/java-inflector.md
index bb4d9dbb2365..309bc1a3dbb9 100644
--- a/docs/generators/java-inflector.md
+++ b/docs/generators/java-inflector.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/java-micronaut-client.md b/docs/generators/java-micronaut-client.md
index 95e4cf76c367..98ce5396a978 100644
--- a/docs/generators/java-micronaut-client.md
+++ b/docs/generators/java-micronaut-client.md
@@ -28,6 +28,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/java-msf4j.md b/docs/generators/java-msf4j.md
index cddf3dde0b7d..d3a7aa4bd218 100644
--- a/docs/generators/java-msf4j.md
+++ b/docs/generators/java-msf4j.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/java-pkmst.md b/docs/generators/java-pkmst.md
index 073b381962c9..1f7b1f7e2627 100644
--- a/docs/generators/java-pkmst.md
+++ b/docs/generators/java-pkmst.md
@@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |eurekaUri|Eureka URI| |null|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |com.prokarma|
diff --git a/docs/generators/java-play-framework.md b/docs/generators/java-play-framework.md
index f7bf3373c7f7..851e0c567a15 100644
--- a/docs/generators/java-play-framework.md
+++ b/docs/generators/java-play-framework.md
@@ -29,6 +29,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |handleExceptions|Add a 'throw exception' to each controller function. Add also a custom error handler where you can put your custom logic| |true|
diff --git a/docs/generators/java-undertow-server.md b/docs/generators/java-undertow-server.md
index 77d069151bdc..f240e9490900 100644
--- a/docs/generators/java-undertow-server.md
+++ b/docs/generators/java-undertow-server.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/java-vertx-web.md b/docs/generators/java-vertx-web.md
index 1c14df7a90f9..011359877603 100644
--- a/docs/generators/java-vertx-web.md
+++ b/docs/generators/java-vertx-web.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/java-vertx.md b/docs/generators/java-vertx.md
index 78b0508c01d4..435c1a122663 100644
--- a/docs/generators/java-vertx.md
+++ b/docs/generators/java-vertx.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/java.md b/docs/generators/java.md
index 4d086325a06f..9f432edc97f3 100644
--- a/docs/generators/java.md
+++ b/docs/generators/java.md
@@ -30,6 +30,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |dynamicOperations|Generate operations dynamically at runtime from an OAS| |false|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |errorObjectType|Error Object type. (This option is for okhttp-gson-next-gen only)| |null|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |gradleProperties|Append additional Gradle proeprties to the gradle.properties file| |null|
diff --git a/docs/generators/javascript-apollo.md b/docs/generators/javascript-apollo.md
index 44a7ccac561a..260fc9809450 100644
--- a/docs/generators/javascript-apollo.md
+++ b/docs/generators/javascript-apollo.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |emitJSDoc|generate JSDoc comments| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |invokerPackage|root package for generated code| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
diff --git a/docs/generators/javascript-closure-angular.md b/docs/generators/javascript-closure-angular.md
index 8d9c3b14a14c..891b35cb9331 100644
--- a/docs/generators/javascript-closure-angular.md
+++ b/docs/generators/javascript-closure-angular.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/javascript-flowtyped.md b/docs/generators/javascript-flowtyped.md
index 51ac05927d3e..a6fcea0533c7 100644
--- a/docs/generators/javascript-flowtyped.md
+++ b/docs/generators/javascript-flowtyped.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name. Only change it if you provide your own run-time code for (de-)serialization of models| |original|
 |npmName|The name under which you want to publish generated npm package. Required to generate a full package| |null|
diff --git a/docs/generators/javascript.md b/docs/generators/javascript.md
index a0bb2d24c952..962b9ffc40ee 100644
--- a/docs/generators/javascript.md
+++ b/docs/generators/javascript.md
@@ -13,6 +13,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |emitJSDoc|generate JSDoc comments| |true|
 |emitModelMethods|generate getters and setters for model properties| |false|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |invokerPackage|root package for generated code| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
diff --git a/docs/generators/jaxrs-cxf-cdi.md b/docs/generators/jaxrs-cxf-cdi.md
index b604285fdbf3..621f0dc3a735 100644
--- a/docs/generators/jaxrs-cxf-cdi.md
+++ b/docs/generators/jaxrs-cxf-cdi.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |generateBuilders|Whether to generate builders for models.| |false|
 |generatePom|Whether to generate pom.xml if the file does not already exist.| |true|
diff --git a/docs/generators/jaxrs-cxf-client.md b/docs/generators/jaxrs-cxf-client.md
index 36393f588aae..ad1c60900364 100644
--- a/docs/generators/jaxrs-cxf-client.md
+++ b/docs/generators/jaxrs-cxf-client.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/jaxrs-cxf-extended.md b/docs/generators/jaxrs-cxf-extended.md
index b8e1da73614d..0eef8cacd4e8 100644
--- a/docs/generators/jaxrs-cxf-extended.md
+++ b/docs/generators/jaxrs-cxf-extended.md
@@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |generateJbossDeploymentDescriptor|Generate Jboss Deployment Descriptor| |false|
 |generateNonSpringApplication|Generate non-Spring application| |false|
diff --git a/docs/generators/jaxrs-cxf.md b/docs/generators/jaxrs-cxf.md
index 5958bcdd2eca..80b178858a31 100644
--- a/docs/generators/jaxrs-cxf.md
+++ b/docs/generators/jaxrs-cxf.md
@@ -27,6 +27,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |generateJbossDeploymentDescriptor|Generate Jboss Deployment Descriptor| |false|
 |generateNonSpringApplication|Generate non-Spring application| |false|
diff --git a/docs/generators/jaxrs-jersey.md b/docs/generators/jaxrs-jersey.md
index 076d72881e30..15584410d1f8 100644
--- a/docs/generators/jaxrs-jersey.md
+++ b/docs/generators/jaxrs-jersey.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |false|
diff --git a/docs/generators/jaxrs-resteasy-eap.md b/docs/generators/jaxrs-resteasy-eap.md
index ed99a6037ef7..247353cbb327 100644
--- a/docs/generators/jaxrs-resteasy-eap.md
+++ b/docs/generators/jaxrs-resteasy-eap.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |generateJbossDeploymentDescriptor|Generate Jboss Deployment Descriptor| |true|
 |groupId|groupId in generated pom.xml| |org.openapitools|
diff --git a/docs/generators/jaxrs-resteasy.md b/docs/generators/jaxrs-resteasy.md
index e7e1a5fd228a..ff9fab072fdc 100644
--- a/docs/generators/jaxrs-resteasy.md
+++ b/docs/generators/jaxrs-resteasy.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |generateJbossDeploymentDescriptor|Generate Jboss Deployment Descriptor| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
diff --git a/docs/generators/jaxrs-spec.md b/docs/generators/jaxrs-spec.md
index 3f7e3c6de57c..621122f6eaa8 100644
--- a/docs/generators/jaxrs-spec.md
+++ b/docs/generators/jaxrs-spec.md
@@ -26,6 +26,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |generateBuilders|Whether to generate builders for models.| |false|
 |generatePom|Whether to generate pom.xml if the file does not already exist.| |true|
diff --git a/docs/generators/jmeter.md b/docs/generators/jmeter.md
index 1618e2c1ad3b..71584a1e793a 100644
--- a/docs/generators/jmeter.md
+++ b/docs/generators/jmeter.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
diff --git a/docs/generators/k6.md b/docs/generators/k6.md
index 4c0e735816df..529527a890c4 100644
--- a/docs/generators/k6.md
+++ b/docs/generators/k6.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
diff --git a/docs/generators/markdown.md b/docs/generators/markdown.md
index 8d7cb9983821..4d87a35f9640 100644
--- a/docs/generators/markdown.md
+++ b/docs/generators/markdown.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
diff --git a/docs/generators/nim.md b/docs/generators/nim.md
index 23957ff2d5bf..3d90efad1598 100644
--- a/docs/generators/nim.md
+++ b/docs/generators/nim.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
diff --git a/docs/generators/nodejs-express-server.md b/docs/generators/nodejs-express-server.md
index a96fa3ec24b7..9fffa3c28b79 100644
--- a/docs/generators/nodejs-express-server.md
+++ b/docs/generators/nodejs-express-server.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |serverPort|TCP port to listen on.| |null|
diff --git a/docs/generators/ocaml.md b/docs/generators/ocaml.md
index f9f922feee3b..597f07b84112 100644
--- a/docs/generators/ocaml.md
+++ b/docs/generators/ocaml.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
diff --git a/docs/generators/openapi-yaml.md b/docs/generators/openapi-yaml.md
index d305a85f0db6..4476c7900003 100644
--- a/docs/generators/openapi-yaml.md
+++ b/docs/generators/openapi-yaml.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |outputFile|Output filename| |openapi/openapi.yaml|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/openapi.md b/docs/generators/openapi.md
index caf9e4c9e6bb..53ea3bf812c3 100644
--- a/docs/generators/openapi.md
+++ b/docs/generators/openapi.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |outputFileName|Output file name| |openapi.json|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/docs/generators/php-dt.md b/docs/generators/php-dt.md
index 6f9dae638045..a4a6eac2b732 100644
--- a/docs/generators/php-dt.md
+++ b/docs/generators/php-dt.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|The version to use in the composer package version field. e.g. 1.2.3| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay\Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
diff --git a/docs/generators/php-laravel.md b/docs/generators/php-laravel.md
index fa6717217adf..09e61d56c132 100644
--- a/docs/generators/php-laravel.md
+++ b/docs/generators/php-laravel.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|The version to use in the composer package version field. e.g. 1.2.3| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay\Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
diff --git a/docs/generators/php-lumen.md b/docs/generators/php-lumen.md
index 1c39477ad47b..562b26a589da 100644
--- a/docs/generators/php-lumen.md
+++ b/docs/generators/php-lumen.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|The version to use in the composer package version field. e.g. 1.2.3| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay\Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
diff --git a/docs/generators/php-mezzio-ph.md b/docs/generators/php-mezzio-ph.md
index 35bedda05f9f..7abb3408bca7 100644
--- a/docs/generators/php-mezzio-ph.md
+++ b/docs/generators/php-mezzio-ph.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|The version to use in the composer package version field. e.g. 1.2.3| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay\Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
diff --git a/docs/generators/php-silex-deprecated.md b/docs/generators/php-silex-deprecated.md
index 9df926cce14e..9b4d5b39b635 100644
--- a/docs/generators/php-silex-deprecated.md
+++ b/docs/generators/php-silex-deprecated.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
diff --git a/docs/generators/php-slim-deprecated.md b/docs/generators/php-slim-deprecated.md
index d6f8b35c7f21..15c4d36ba80f 100644
--- a/docs/generators/php-slim-deprecated.md
+++ b/docs/generators/php-slim-deprecated.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|The version to use in the composer package version field. e.g. 1.2.3| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay\Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
diff --git a/docs/generators/php-slim4.md b/docs/generators/php-slim4.md
index ae6cc1cb6569..ca1bd3b6a101 100644
--- a/docs/generators/php-slim4.md
+++ b/docs/generators/php-slim4.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|The version to use in the composer package version field. e.g. 1.2.3| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay\Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
diff --git a/docs/generators/php-symfony.md b/docs/generators/php-symfony.md
index 4d268ab389ee..0a231dbd2e49 100644
--- a/docs/generators/php-symfony.md
+++ b/docs/generators/php-symfony.md
@@ -16,6 +16,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |composerVendorName|The vendor name used in the composer package name. The template uses {{composerVendorName}}/{{composerProjectName}} for the composer package name. e.g. yaypets| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay\Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
diff --git a/docs/generators/php.md b/docs/generators/php.md
index dcee69588f4b..c84e12c36f66 100644
--- a/docs/generators/php.md
+++ b/docs/generators/php.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |artifactVersion|The version to use in the composer package version field. e.g. 1.2.3| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hideGenerationTimestamp|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |true|
 |invokerPackage|The main namespace to use for all classes. e.g. Yay\Pets| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
diff --git a/docs/generators/plantuml.md b/docs/generators/plantuml.md
index 2413b540ef09..7a37ad0d187f 100644
--- a/docs/generators/plantuml.md
+++ b/docs/generators/plantuml.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
 |sortModelPropertiesByRequiredFlag|Sort model properties to place required parameters before optional parameters.| |true|
diff --git a/docs/generators/python-aiohttp.md b/docs/generators/python-aiohttp.md
index e986c14fd901..14ffd174221f 100644
--- a/docs/generators/python-aiohttp.md
+++ b/docs/generators/python-aiohttp.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |defaultController|default controller| |default_controller|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |featureCORS|use flask-cors for handling CORS requests| |false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |packageName|python package name (convention: snake_case).| |openapi_server|
diff --git a/docs/generators/python-blueplanet.md b/docs/generators/python-blueplanet.md
index 020c239e3081..049e3424ebbf 100644
--- a/docs/generators/python-blueplanet.md
+++ b/docs/generators/python-blueplanet.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |defaultController|default controller| |default_controller|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |featureCORS|use flask-cors for handling CORS requests| |false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |packageName|python package name (convention: snake_case).| |openapi_server|
diff --git a/docs/generators/python-fastapi.md b/docs/generators/python-fastapi.md
index 2143321f2d7d..4e321ff9e59e 100644
--- a/docs/generators/python-fastapi.md
+++ b/docs/generators/python-fastapi.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |packageName|python package name (convention: snake_case).| |openapi_server|
 |packageVersion|python package version.| |1.0.0|
diff --git a/docs/generators/python-flask.md b/docs/generators/python-flask.md
index f65ec823a837..a0a5f44b20a3 100644
--- a/docs/generators/python-flask.md
+++ b/docs/generators/python-flask.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |defaultController|default controller| |default_controller|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |featureCORS|use flask-cors for handling CORS requests| |false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |packageName|python package name (convention: snake_case).| |openapi_server|
diff --git a/docs/generators/ruby.md b/docs/generators/ruby.md
index 5cd52c8c27af..6937905b9e3d 100644
--- a/docs/generators/ruby.md
+++ b/docs/generators/ruby.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |gemAuthor|gem author (only one is supported).| |OpenAPI-Generator|
 |gemAuthorEmail|gem author email (only one is supported).| |null|
 |gemDescription|gem description. | |This gem maps to a REST API|
diff --git a/docs/generators/scala-akka-http-server.md b/docs/generators/scala-akka-http-server.md
index 3727fc6fdf60..3d27821c2315 100644
--- a/docs/generators/scala-akka-http-server.md
+++ b/docs/generators/scala-akka-http-server.md
@@ -16,6 +16,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for JDK 1.8+)</dd></dl>|java8|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |invokerPackage|root package for generated code| |org.openapitools.server|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
diff --git a/docs/generators/scala-akka.md b/docs/generators/scala-akka.md
index f2c9cecdab97..1cc19c6216da 100644
--- a/docs/generators/scala-akka.md
+++ b/docs/generators/scala-akka.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for JDK 1.8+)</dd></dl>|java8|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |mainPackage|Top-level package name, which defines 'apiPackage', 'modelPackage', 'invokerPackage'| |org.openapitools.client|
 |modelPackage|package for generated models| |null|
diff --git a/docs/generators/scala-gatling.md b/docs/generators/scala-gatling.md
index 2477cb6848e2..6daaef5d657e 100644
--- a/docs/generators/scala-gatling.md
+++ b/docs/generators/scala-gatling.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for JDK 1.8+)</dd></dl>|java8|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |camelCase|
diff --git a/docs/generators/scala-httpclient-deprecated.md b/docs/generators/scala-httpclient-deprecated.md
index adf4649ffcc4..4bd12dca9552 100644
--- a/docs/generators/scala-httpclient-deprecated.md
+++ b/docs/generators/scala-httpclient-deprecated.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for JDK 1.8+)</dd></dl>|java8|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |camelCase|
diff --git a/docs/generators/scala-lagom-server.md b/docs/generators/scala-lagom-server.md
index 8c583afcaac0..ed197a23e5eb 100644
--- a/docs/generators/scala-lagom-server.md
+++ b/docs/generators/scala-lagom-server.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for JDK 1.8+)</dd></dl>|java8|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |camelCase|
diff --git a/docs/generators/scala-play-server.md b/docs/generators/scala-play-server.md
index 7be64e0f108e..aeab7fd2538c 100644
--- a/docs/generators/scala-play-server.md
+++ b/docs/generators/scala-play-server.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |basePackage|Base package in which supporting classes are generated.| |org.openapitools|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |generateCustomExceptions|If set, generates custom exception types.| |true|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
diff --git a/docs/generators/scala-sttp.md b/docs/generators/scala-sttp.md
index 0e12f7695d40..9425f8f5c973 100644
--- a/docs/generators/scala-sttp.md
+++ b/docs/generators/scala-sttp.md
@@ -13,6 +13,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for JDK 1.8+)</dd></dl>|java8|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |jodaTimeVersion|The version of joda-time library| |2.10.10|
 |json4sVersion|The version of json4s library| |3.6.11|
 |jsonLibrary|Json library to use. Possible values are: json4s and circe.| |json4s|
diff --git a/docs/generators/scalatra.md b/docs/generators/scalatra.md
index aab1bd98c224..9159c798f233 100644
--- a/docs/generators/scalatra.md
+++ b/docs/generators/scalatra.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for JDK 1.8+)</dd></dl>|java8|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |camelCase|
diff --git a/docs/generators/scalaz.md b/docs/generators/scalaz.md
index 87dc8b0e5e48..18520f5e3b3f 100644
--- a/docs/generators/scalaz.md
+++ b/docs/generators/scalaz.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |dateLibrary|Option. Date library to use|<dl><dt>**joda**</dt><dd>Joda (for legacy app)</dd><dt>**java8**</dt><dd>Java 8 native JSR310 (preferred for JDK 1.8+)</dd></dl>|java8|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPackage|package for generated models| |null|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |camelCase|
diff --git a/docs/generators/spring.md b/docs/generators/spring.md
index 8f834fdf27dd..34e4a6a266cb 100644
--- a/docs/generators/spring.md
+++ b/docs/generators/spring.md
@@ -31,6 +31,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |discriminatorCaseSensitive|Whether the discriminator value lookup should be case-sensitive or not. This option only works for Java API client| |true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fullJavaUtil|whether to use fully qualified name for classes under java.util. This option only works for Java API client| |false|
 |groupId|groupId in generated pom.xml| |org.openapitools|
 |hateoas|Use Spring HATEOAS library to allow adding HATEOAS links| |false|
diff --git a/docs/generators/swift4-deprecated.md b/docs/generators/swift4-deprecated.md
index ef9fed5d5a8f..cf1e1f65df40 100644
--- a/docs/generators/swift4-deprecated.md
+++ b/docs/generators/swift4-deprecated.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |lenientTypeCast|Accept and cast values for simple types (string-&gt;bool, string-&gt;int, int-&gt;string)| |false|
diff --git a/docs/generators/swift5.md b/docs/generators/swift5.md
index 9404a2fd458d..95f50fca7fc1 100644
--- a/docs/generators/swift5.md
+++ b/docs/generators/swift5.md
@@ -11,7 +11,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |apiNamePrefix|Prefix that will be appended to all API names ('tags'). Default: empty string. e.g. Pet =&gt; Pet.| |null|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
-|generateFrozenEnums|Generate frozen enums (default: true)| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |generateModelAdditionalProperties|Generate model additional properties (default: true)| |true|
 |hashableModels|Make hashable models (default: true)| |true|
 |hideGenerationTimestamp|Hides the generation timestamp when files are generated.| |true|
diff --git a/docs/generators/typescript-angular.md b/docs/generators/typescript-angular.md
index 2083b09cadf4..9421c54646ed 100644
--- a/docs/generators/typescript-angular.md
+++ b/docs/generators/typescript-angular.md
@@ -14,6 +14,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fileNaming|Naming convention for the output files: 'camelCase', 'kebab-case'.| |camelCase|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelFileSuffix|The suffix of the file of the generated model (model&lt;suffix&gt;.ts).| |null|
diff --git a/docs/generators/typescript-angularjs-deprecated.md b/docs/generators/typescript-angularjs-deprecated.md
index 9363a6958da7..c094849a0781 100644
--- a/docs/generators/typescript-angularjs-deprecated.md
+++ b/docs/generators/typescript-angularjs-deprecated.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name. Only change it if you provide your own run-time code for (de-)serialization of models| |original|
 |nullSafeAdditionalProps|Set to make additional properties types declare that their indexer may return undefined| |false|
diff --git a/docs/generators/typescript-aurelia.md b/docs/generators/typescript-aurelia.md
index aaad28dd75bc..23b71ae41a38 100644
--- a/docs/generators/typescript-aurelia.md
+++ b/docs/generators/typescript-aurelia.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name. Only change it if you provide your own run-time code for (de-)serialization of models| |original|
 |npmName|The name under which you want to publish generated npm package. Required to generate a full package| |null|
diff --git a/docs/generators/typescript-axios.md b/docs/generators/typescript-axios.md
index 8dfc77b52df8..3cfeda785802 100644
--- a/docs/generators/typescript-axios.md
+++ b/docs/generators/typescript-axios.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |npmName|The name under which you want to publish generated npm package. Required to generate a full package| |null|
 |npmRepository|Use this property to set an url of your private npmRepo in the package.json| |null|
diff --git a/docs/generators/typescript-fetch.md b/docs/generators/typescript-fetch.md
index f8e9cd2328ad..3fe83380da4a 100644
--- a/docs/generators/typescript-fetch.md
+++ b/docs/generators/typescript-fetch.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |camelCase|
 |npmName|The name under which you want to publish generated npm package. Required to generate a full package| |null|
diff --git a/docs/generators/typescript-inversify.md b/docs/generators/typescript-inversify.md
index 38077cb2b40a..21e44eac43f7 100644
--- a/docs/generators/typescript-inversify.md
+++ b/docs/generators/typescript-inversify.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name. Only change it if you provide your own run-time code for (de-)serialization of models| |original|
 |npmName|The name under which you want to publish generated npm package. Required to generate a full package| |null|
diff --git a/docs/generators/typescript-jquery.md b/docs/generators/typescript-jquery.md
index fcff7abe194b..030fdd2e572c 100644
--- a/docs/generators/typescript-jquery.md
+++ b/docs/generators/typescript-jquery.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |jqueryAlreadyImported|When using this in legacy app using mix of typescript and javascript, this will only declare jquery and not import it| |false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name. Only change it if you provide your own run-time code for (de-)serialization of models| |original|
diff --git a/docs/generators/typescript-nestjs.md b/docs/generators/typescript-nestjs.md
index 50e9acb16754..a3f0b52a05da 100644
--- a/docs/generators/typescript-nestjs.md
+++ b/docs/generators/typescript-nestjs.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fileNaming|Naming convention for the output files: 'camelCase', 'kebab-case'.| |camelCase|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelFileSuffix|The suffix of the file of the generated model (model&lt;suffix&gt;.ts).| |null|
diff --git a/docs/generators/typescript-node.md b/docs/generators/typescript-node.md
index 388dfd551bde..5de270453127 100644
--- a/docs/generators/typescript-node.md
+++ b/docs/generators/typescript-node.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |camelCase|
 |npmName|The name under which you want to publish generated npm package. Required to generate a full package| |null|
diff --git a/docs/generators/typescript-redux-query.md b/docs/generators/typescript-redux-query.md
index dd79fa1a433d..f2266c09703c 100644
--- a/docs/generators/typescript-redux-query.md
+++ b/docs/generators/typescript-redux-query.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name| |camelCase|
 |npmName|The name under which you want to publish generated npm package. Required to generate a full package| |null|
diff --git a/docs/generators/typescript-rxjs.md b/docs/generators/typescript-rxjs.md
index 509991799854..40921ae7f58a 100644
--- a/docs/generators/typescript-rxjs.md
+++ b/docs/generators/typescript-rxjs.md
@@ -12,6 +12,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
 |enumNameSuffix|Suffix that will be appended to all enum names.| |Enum|
 |enumPropertyNaming|Naming convention for enum properties: 'camelCase', 'PascalCase', 'snake_case', 'UPPERCASE', and 'original'| |PascalCase|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |modelPropertyNaming|Naming convention for the property: 'camelCase', 'PascalCase', 'snake_case' and 'original', which keeps the original name. Only change it if you provide your own run-time code for (de-)serialization of models| |original|
 |npmName|The name under which you want to publish generated npm package. Required to generate a full package| |null|
diff --git a/docs/generators/typescript.md b/docs/generators/typescript.md
index bff28b73905b..9c6eea23c032 100644
--- a/docs/generators/typescript.md
+++ b/docs/generators/typescript.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |fileContentDataType|Specifies the type to use for the content of a file - i.e. Blob (Browser, Deno) / Buffer (node)| |Buffer|
 |framework|Specify the framework which should be used in the client code.|<dl><dt>**fetch-api**</dt><dd>fetch-api</dd><dt>**jquery**</dt><dd>jquery</dd></dl>|fetch-api|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
diff --git a/docs/generators/wsdl-schema.md b/docs/generators/wsdl-schema.md
index 7842f8567492..a2af11398624 100644
--- a/docs/generators/wsdl-schema.md
+++ b/docs/generators/wsdl-schema.md
@@ -10,6 +10,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |allowUnicodeIdentifiers|boolean, toggles whether unicode identifiers are allowed in names or not, default is false| |false|
 |disallowAdditionalPropertiesIfNotPresent|If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.|<dl><dt>**false**</dt><dd>The 'additionalProperties' implementation is compliant with the OAS and JSON schema specifications.</dd><dt>**true**</dt><dd>Keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.</dd></dl>|true|
 |ensureUniqueParams|Whether to ensure parameter names are unique in an operation (rename parameters that are not).| |true|
+|enumUnknownDefaultCase|If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.|<dl><dt>**false**</dt><dd>No changes to the enum's are made, this is the default option.</dd><dt>**true**</dt><dd>With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.</dd></dl>|false|
 |hostname|the hostname of the service| |null|
 |legacyDiscriminatorBehavior|Set to false for generators with better support for discriminators. (Python, Java, Go, PowerShell, C#have this enabled by default).|<dl><dt>**true**</dt><dd>The mapping in the discriminator includes descendent schemas that allOf inherit from self and the discriminator mapping schemas in the OAS document.</dd><dt>**false**</dt><dd>The mapping in the discriminator includes any descendent schemas that allOf inherit from self, any oneOf schemas, any anyOf schemas, any x-discriminator-values, and the discriminator mapping schemas in the OAS document AND Codegen validates that oneOf and anyOf schemas contain the required discriminator and throws an error if the discriminator is missing.</dd></dl>|true|
 |prependFormOrBodyParameters|Add form or body parameters to the beginning of the parameter list.| |false|
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenConstants.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenConstants.java
index bb7aa069fe7a..ffbd0c5e0a4b 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenConstants.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/CodegenConstants.java
@@ -386,6 +386,12 @@ public static enum ENUM_PROPERTY_NAMING_TYPE {camelCase, PascalCase, snake_case,
     public static final String DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT_DESC =
         "If false, the 'additionalProperties' implementation (set to true by default) is compliant with the OAS and JSON schema specifications. " +
         "If true (default), keep the old (incorrect) behaviour that 'additionalProperties' is set to false by default.";
+
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE = "enumUnknownDefaultCase";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_DESC =
+            "If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response." +
+            "With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.";
+
     public static final String USE_ONEOF_DISCRIMINATOR_LOOKUP = "useOneOfDiscriminatorLookup";
     public static final String USE_ONEOF_DISCRIMINATOR_LOOKUP_DESC = "Use the discriminator's mapping in oneOf to speed up the model lookup. IMPORTANT: Validation (e.g. one and only one match in oneOf's schemas) will be skipped.";
 }
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
index a9780140f4c9..e28f4a03c33e 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
@@ -253,6 +253,11 @@ apiTemplateFiles are for API outputs only (controllers/handlers).
     // See CodegenConstants.java for more details.
     protected boolean disallowAdditionalPropertiesIfNotPresent = true;
 
+    // If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.
+    // With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.
+    protected boolean enumUnknownDefaultCase = false;
+    protected String enumUnknownDefaultCaseName = "unknown_default_open_api";
+
     // make openapi available to all methods
     protected OpenAPI openAPI;
 
@@ -376,6 +381,10 @@ public void processOpts() {
             this.setDisallowAdditionalPropertiesIfNotPresent(Boolean.parseBoolean(additionalProperties
                     .get(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT).toString()));
         }
+        if (additionalProperties.containsKey(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE)) {
+            this.setEnumUnknownDefaultCase(Boolean.parseBoolean(additionalProperties
+                    .get(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE).toString()));
+        }
     }
 
     /***
@@ -1302,6 +1311,14 @@ public void setDisallowAdditionalPropertiesIfNotPresent(boolean val) {
         this.disallowAdditionalPropertiesIfNotPresent = val;
     }
 
+    public Boolean getEnumUnknownDefaultCase() {
+        return enumUnknownDefaultCase;
+    }
+
+    public void setEnumUnknownDefaultCase(boolean val) {
+        this.enumUnknownDefaultCase = val;
+    }
+
     public Boolean getAllowUnicodeIdentifiers() {
         return allowUnicodeIdentifiers;
     }
@@ -1639,6 +1656,18 @@ public DefaultCodegen() {
         cliOptions.add(disallowAdditionalPropertiesIfNotPresentOpt);
         this.setDisallowAdditionalPropertiesIfNotPresent(true);
 
+        CliOption enumUnknownDefaultCaseOpt = CliOption.newBoolean(
+                CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE,
+                CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE_DESC).defaultValue(Boolean.FALSE.toString());
+        Map<String, String> enumUnknownDefaultCaseOpts = new HashMap<>();
+        enumUnknownDefaultCaseOpts.put("false",
+                "No changes to the enum's are made, this is the default option.");
+        enumUnknownDefaultCaseOpts.put("true",
+                "With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the enum case sent by the server is not known by the client/spec, can safely be decoded to this case.");
+        enumUnknownDefaultCaseOpt.setEnum(enumUnknownDefaultCaseOpts);
+        cliOptions.add(enumUnknownDefaultCaseOpt);
+        this.setEnumUnknownDefaultCase(false);
+
         // initialize special character mapping
         initializeSpecialCharacterMapping();
 
@@ -5888,6 +5917,32 @@ protected List<Map<String, Object>> buildEnumVars(List<Object> values, String da
             enumVar.put("isString", isDataTypeString(dataType));
             enumVars.add(enumVar);
         }
+
+        if (enumUnknownDefaultCase) {
+            // If the server adds new enum cases, that are unknown by an old spec/client, the client will fail to parse the network response.
+            // With this option enabled, each enum will have a new case, 'unknown_default_open_api', so that when the server sends an enum case that is not known by the client/spec, they can safely fallback to this case.
+            Map<String, Object> enumVar = new HashMap<>();
+            String enumName = enumUnknownDefaultCaseName;
+
+            String enumValue;
+            if (isDataTypeString(dataType)) {
+                enumValue = enumUnknownDefaultCaseName;
+            } else {
+                // This is a dummy value that attempts to avoid collisions with previously specified cases.
+                // Int.max / 192
+                // The number 192 that is used to calculate this random value, is the Swift Evolution proposal for frozen/non-frozen enums.
+                // [SE-0192](https://github.com/apple/swift-evolution/blob/master/proposals/0192-non-exhaustive-enums.md)
+                // Since this functionality was born in the Swift 5 generator and latter on broth to all generatorss
+                // https://github.com/OpenAPITools/openapi-generator/pull/11013
+                enumValue = String.valueOf(11184809);
+            }
+
+            enumVar.put("name", toEnumVarName(enumName, dataType));
+            enumVar.put("value", toEnumValue(enumValue, dataType));
+            enumVar.put("isString", isDataTypeString(dataType));
+            enumVars.add(enumVar);
+        }
+
         return enumVars;
     }
 
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
index b0d272d075b4..9ebab55c3f33 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
@@ -582,6 +582,9 @@ private void addSupportingSerializerAdapters(final String infrastructureFolder)
 
         switch (getSerializationLibrary()) {
             case moshi:
+                if (enumUnknownDefaultCase) {
+                    supportingFiles.add(new SupportingFile("jvm-common/infrastructure/SerializerHelper.kt.mustache", infrastructureFolder, "SerializerHelper.kt"));
+                }
                 supportingFiles.add(new SupportingFile("jvm-common/infrastructure/UUIDAdapter.kt.mustache", infrastructureFolder, "UUIDAdapter.kt"));
                 supportingFiles.add(new SupportingFile("jvm-common/infrastructure/LocalDateAdapter.kt.mustache", infrastructureFolder, "LocalDateAdapter.kt"));
                 supportingFiles.add(new SupportingFile("jvm-common/infrastructure/LocalDateTimeAdapter.kt.mustache", infrastructureFolder, "LocalDateTimeAdapter.kt"));
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java
index 4610b7ded05f..21e7a03c8817 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/Swift5ClientCodegen.java
@@ -66,7 +66,6 @@ public class Swift5ClientCodegen extends DefaultCodegen implements CodegenConfig
     public static final String SWIFT_PACKAGE_PATH = "swiftPackagePath";
     public static final String USE_CLASSES = "useClasses";
     public static final String USE_BACKTICK_ESCAPES = "useBacktickEscapes";
-    public static final String GENERATE_FROZEN_ENUMS = "generateFrozenEnums";
     public static final String GENERATE_MODEL_ADDITIONAL_PROPERTIES = "generateModelAdditionalProperties";
     public static final String HASHABLE_MODELS = "hashableModels";
     public static final String MAP_FILE_BINARY_TO_DATA = "mapFileBinaryToData";
@@ -91,7 +90,6 @@ public class Swift5ClientCodegen extends DefaultCodegen implements CodegenConfig
     protected boolean useClasses = false;
     protected boolean useBacktickEscapes = false;
     protected boolean generateModelAdditionalProperties = true;
-    protected boolean generateFrozenEnums = true;
     protected boolean hashableModels = true;
     protected boolean mapFileBinaryToData = false;
     protected String[] responseAs = new String[0];
@@ -283,9 +281,6 @@ public Swift5ClientCodegen() {
         cliOptions.add(new CliOption(USE_BACKTICK_ESCAPES,
                 "Escape reserved words using backticks (default: false)")
                 .defaultValue(Boolean.FALSE.toString()));
-        cliOptions.add(new CliOption(GENERATE_FROZEN_ENUMS,
-                "Generate frozen enums (default: true)")
-                .defaultValue(Boolean.TRUE.toString()));
         cliOptions.add(new CliOption(GENERATE_MODEL_ADDITIONAL_PROPERTIES,
                 "Generate model additional properties (default: true)")
                 .defaultValue(Boolean.TRUE.toString()));
@@ -490,13 +485,6 @@ public void processOpts() {
             setUseBacktickEscapes(convertPropertyToBooleanAndWriteBack(USE_BACKTICK_ESCAPES));
         }
 
-        // Setup generateFrozenEnums option. If true, enums will strictly include
-        // cases matching the spec. If false, enums will also include an extra catch-all case.
-        if (additionalProperties.containsKey(GENERATE_FROZEN_ENUMS)) {
-            setGenerateFrozenEnums(convertPropertyToBooleanAndWriteBack(GENERATE_FROZEN_ENUMS));
-        }
-        additionalProperties.put(GENERATE_FROZEN_ENUMS, generateFrozenEnums);
-
         if (additionalProperties.containsKey(GENERATE_MODEL_ADDITIONAL_PROPERTIES)) {
             setGenerateModelAdditionalProperties(convertPropertyToBooleanAndWriteBack(GENERATE_MODEL_ADDITIONAL_PROPERTIES));
         }
@@ -955,10 +943,6 @@ public void setUseBacktickEscapes(boolean useBacktickEscapes) {
         this.useBacktickEscapes = useBacktickEscapes;
     }
 
-    public void setGenerateFrozenEnums(boolean generateFrozenEnums) {
-        this.generateFrozenEnums = generateFrozenEnums;
-    }
-
     public void setGenerateModelAdditionalProperties(boolean generateModelAdditionalProperties) {
         this.generateModelAdditionalProperties = generateModelAdditionalProperties;
     }
@@ -988,6 +972,12 @@ public String toEnumVarName(String name, String datatype) {
             return "empty";
         }
 
+        if (enumUnknownDefaultCase) {
+            if (name.equals(enumUnknownDefaultCaseName)) {
+                return camelize(name, true);
+            }
+        }
+
         // Reserved Name
         String nameLowercase = StringUtils.lowerCase(name);
         if (isReservedWord(nameLowercase)) {
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache
index e3e570e7a0ca..884e16846b14 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache
@@ -2,6 +2,9 @@ package {{packageName}}.infrastructure
 
 {{#moshi}}
 import com.squareup.moshi.Moshi
+{{#enumUnknownDefaultCase}}
+import com.squareup.moshi.adapters.EnumJsonAdapter
+{{/enumUnknownDefaultCase}}
 {{^moshiCodeGen}}
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
 {{/moshiCodeGen}}
@@ -68,6 +71,9 @@ import java.util.concurrent.atomic.AtomicLong
 
     @JvmStatic
     val moshi: Moshi by lazy {
+{{#enumUnknownDefaultCase}}
+        SerializerHelper.addEnumUnknownDefaultCase(moshiBuilder)
+{{/enumUnknownDefaultCase}}
         moshiBuilder.build()
     }
 {{/moshi}}
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/SerializerHelper.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/SerializerHelper.kt.mustache
new file mode 100644
index 000000000000..fbf67a75dde9
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/SerializerHelper.kt.mustache
@@ -0,0 +1,50 @@
+package {{packageName}}.infrastructure
+
+{{#moshi}}
+import com.squareup.moshi.Moshi
+{{#enumUnknownDefaultCase}}
+import com.squareup.moshi.adapters.EnumJsonAdapter
+{{/enumUnknownDefaultCase}}
+{{/moshi}}
+
+{{#nonPublicApi}}internal {{/nonPublicApi}}object SerializerHelper {
+{{#moshi}}
+    fun addEnumUnknownDefaultCase(moshiBuilder: Moshi.Builder): Moshi.Builder {
+        return moshiBuilder
+{{#enumUnknownDefaultCase}}
+{{#models}}
+{{#model}}
+{{#isEnum}}
+{{#allowableValues}}
+{{#enumVars}}
+{{#-last}}
+            .add({{modelPackage}}.{{classname}}::class.java, EnumJsonAdapter.create({{modelPackage}}.{{classname}}::class.java)
+                .withUnknownFallback({{modelPackage}}.{{classname}}.{{&name}}))
+{{/-last}}
+{{/enumVars}}
+{{/allowableValues}}
+{{/isEnum}}
+{{^isEnum}}
+{{^isAlias}}
+{{#hasEnums}}
+{{#vars}}
+{{#isEnum}}
+{{#allowableValues}}
+{{#enumVars}}
+{{#-last}}
+            .add({{modelPackage}}.{{classname}}.{{{nameInCamelCase}}}::class.java, EnumJsonAdapter.create({{modelPackage}}.{{classname}}.{{{nameInCamelCase}}}::class.java)
+                .withUnknownFallback({{modelPackage}}.{{classname}}.{{{nameInCamelCase}}}.{{&name}}))
+{{/-last}}
+{{/enumVars}}
+{{/allowableValues}}
+{{/isEnum}}
+{{/vars}}
+{{/hasEnums}}
+{{/isAlias}}
+{{/isEnum}}
+{{/model}}
+{{/models}}
+{{/enumUnknownDefaultCase}}
+    }
+{{/moshi}}
+}
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
index f7a01d9dfbb9..7817289fa11a 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/api.mustache
@@ -6,6 +6,25 @@ import java.io.IOException
 {{#imports}}import {{import}}
 {{/imports}}
 
+{{^multiplatform}}
+{{#gson}}
+import com.google.gson.annotations.SerializedName
+{{/gson}}
+{{#moshi}}
+import com.squareup.moshi.Json
+{{/moshi}}
+{{#jackson}}
+import com.fasterxml.jackson.annotation.JsonProperty
+{{/jackson}}
+{{#kotlinx_serialization}}
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+{{/kotlinx_serialization}}
+{{/multiplatform}}
+{{#multiplatform}}
+import kotlinx.serialization.*
+{{/multiplatform}}
+
 {{^doNotUseRxAndCoroutines}}
 {{#useCoroutines}}
 import kotlinx.coroutines.Dispatchers
@@ -35,6 +54,65 @@ import {{packageName}}.infrastructure.toMultiValue
     }
 
     {{#operation}}
+    {{#allParams}}
+    {{#isEnum}}
+    /**
+     * enum for parameter {{paramName}}
+     */
+     {{#nonPublicApi}}internal {{/nonPublicApi}}enum class {{enumName}}_{{operationId}}(val value: {{^isContainer}}{{dataType}}{{/isContainer}}{{#isContainer}}kotlin.String{{/isContainer}}) {
+     {{^enumUnknownDefaultCase}}
+     {{#allowableValues}}
+     {{#enumVars}}
+         {{^multiplatform}}
+         {{#moshi}}
+         @Json(name = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/moshi}}
+         {{#gson}}
+         @SerializedName(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/gson}}
+         {{#jackson}}
+         @JsonProperty(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/jackson}}
+         {{#kotlinx_serialization}}
+         @SerialName(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/kotlinx_serialization}}
+         {{/multiplatform}}
+         {{#multiplatform}}
+         @SerialName(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/multiplatform}}
+     {{/enumVars}}
+     {{/allowableValues}}
+     {{/enumUnknownDefaultCase}}
+     {{#enumUnknownDefaultCase}}
+     {{#allowableValues}}
+     {{#enumVars}}
+     {{^-last}}
+         {{^multiplatform}}
+         {{#moshi}}
+         @Json(name = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/moshi}}
+         {{#gson}}
+         @SerializedName(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/gson}}
+         {{#jackson}}
+         @JsonProperty(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/jackson}}
+         {{#kotlinx_serialization}}
+         @SerialName(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/kotlinx_serialization}}
+         {{/multiplatform}}
+         {{#multiplatform}}
+         @SerialName(value = {{^isString}}"{{/isString}}{{{value}}}{{^isString}}"{{/isString}}) {{&name}}({{{value}}}),
+         {{/multiplatform}}
+     {{/-last}}
+     {{/enumVars}}
+     {{/allowableValues}}
+     {{/enumUnknownDefaultCase}}
+         ;
+     }
+
+    {{/isEnum}}
+    {{/allParams}}
     /**
     * {{summary}}
     * {{notes}}
@@ -51,7 +129,7 @@ import {{packageName}}.infrastructure.toMultiValue
     {{#isDeprecated}}
     @Deprecated(message = "This operation is deprecated.")
     {{/isDeprecated}}
-    {{^doNotUseRxAndCoroutines}}{{#useCoroutines}}suspend {{/useCoroutines}}{{/doNotUseRxAndCoroutines}}fun {{operationId}}({{#allParams}}{{{paramName}}}: {{{dataType}}}{{^required}}?{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) : {{#returnType}}{{{returnType}}}{{#nullableReturnType}}?{{/nullableReturnType}}{{/returnType}}{{^returnType}}Unit{{/returnType}}{{^doNotUseRxAndCoroutines}}{{#useCoroutines}} = withContext(Dispatchers.IO){{/useCoroutines}}{{/doNotUseRxAndCoroutines}} {
+    {{^doNotUseRxAndCoroutines}}{{#useCoroutines}}suspend {{/useCoroutines}}{{/doNotUseRxAndCoroutines}}fun {{operationId}}({{#allParams}}{{paramName}}: {{#isEnum}}{{#isContainer}}kotlin.collections.List<{{enumName}}_{{operationId}}>{{/isContainer}}{{^isContainer}}{{enumName}}_{{operationId}}{{/isContainer}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}{{^required}}?{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) : {{#returnType}}{{{returnType}}}{{#nullableReturnType}}?{{/nullableReturnType}}{{/returnType}}{{^returnType}}Unit{{/returnType}}{{^doNotUseRxAndCoroutines}}{{#useCoroutines}} = withContext(Dispatchers.IO){{/useCoroutines}}{{/doNotUseRxAndCoroutines}} {
         {{#isDeprecated}}
         @Suppress("DEPRECATION")
         {{/isDeprecated}}
@@ -85,7 +163,7 @@ import {{packageName}}.infrastructure.toMultiValue
     {{#isDeprecated}}
     @Deprecated(message = "This operation is deprecated.")
     {{/isDeprecated}}
-    {{^doNotUseRxAndCoroutines}}{{#useCoroutines}}suspend {{/useCoroutines}}{{/doNotUseRxAndCoroutines}}fun {{operationId}}WithHttpInfo({{#allParams}}{{{paramName}}}: {{{dataType}}}{{^required}}?{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) : ApiResponse<{{#returnType}}{{{returnType}}}?{{/returnType}}{{^returnType}}Unit?{{/returnType}}>{{^doNotUseRxAndCoroutines}}{{#useCoroutines}} = withContext(Dispatchers.IO){{/useCoroutines}}{{/doNotUseRxAndCoroutines}} {
+    {{^doNotUseRxAndCoroutines}}{{#useCoroutines}}suspend {{/useCoroutines}}{{/doNotUseRxAndCoroutines}}fun {{operationId}}WithHttpInfo({{#allParams}}{{paramName}}: {{#isEnum}}{{#isContainer}}kotlin.collections.List<{{enumName}}_{{operationId}}>{{/isContainer}}{{^isContainer}}{{enumName}}_{{operationId}}{{/isContainer}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}{{^required}}?{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) : ApiResponse<{{#returnType}}{{{returnType}}}?{{/returnType}}{{^returnType}}Unit?{{/returnType}}>{{^doNotUseRxAndCoroutines}}{{#useCoroutines}} = withContext(Dispatchers.IO){{/useCoroutines}}{{/doNotUseRxAndCoroutines}} {
         {{#isDeprecated}}
         @Suppress("DEPRECATION")
         {{/isDeprecated}}
@@ -105,10 +183,10 @@ import {{packageName}}.infrastructure.toMultiValue
     {{#isDeprecated}}
     @Deprecated(message = "This operation is deprecated.")
     {{/isDeprecated}}
-    fun {{operationId}}RequestConfig({{#allParams}}{{{paramName}}}: {{{dataType}}}{{^required}}?{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) : RequestConfig<{{#hasBodyParam}}{{#bodyParams}}{{{dataType}}}{{/bodyParams}}{{/hasBodyParam}}{{^hasBodyParam}}{{^hasFormParams}}Unit{{/hasFormParams}}{{#hasFormParams}}Map<String, Any?>{{/hasFormParams}}{{/hasBodyParam}}> {
+    fun {{operationId}}RequestConfig({{#allParams}}{{paramName}}: {{#isEnum}}{{#isContainer}}kotlin.collections.List<{{enumName}}_{{operationId}}>{{/isContainer}}{{^isContainer}}{{enumName}}_{{operationId}}{{/isContainer}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}{{^required}}?{{/required}}{{^-last}}, {{/-last}}{{/allParams}}) : RequestConfig<{{#hasBodyParam}}{{#bodyParams}}{{{dataType}}}{{/bodyParams}}{{/hasBodyParam}}{{^hasBodyParam}}{{^hasFormParams}}Unit{{/hasFormParams}}{{#hasFormParams}}Map<String, Any?>{{/hasFormParams}}{{/hasBodyParam}}> {
         val localVariableBody = {{#hasBodyParam}}{{#bodyParams}}{{{paramName}}}{{/bodyParams}}{{/hasBodyParam}}{{^hasBodyParam}}{{^hasFormParams}}null{{/hasFormParams}}{{#hasFormParams}}mapOf({{#formParams}}"{{{baseName}}}" to {{{paramName}}}{{^-last}}, {{/-last}}{{/formParams}}){{/hasFormParams}}{{/hasBodyParam}}
         val localVariableQuery: MultiValueMap = {{^hasQueryParams}}mutableMapOf()
-{{/hasQueryParams}}{{#hasQueryParams}}mutableMapOf<kotlin.String, List<kotlin.String>>()
+{{/hasQueryParams}}{{#hasQueryParams}}mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 {{#queryParams}}
                 {{^required}}
diff --git a/modules/openapi-generator/src/main/resources/swift5/api.mustache b/modules/openapi-generator/src/main/resources/swift5/api.mustache
index e5cd7ea4490d..9cf516b0c26e 100644
--- a/modules/openapi-generator/src/main/resources/swift5/api.mustache
+++ b/modules/openapi-generator/src/main/resources/swift5/api.mustache
@@ -30,11 +30,22 @@ extension {{projectName}}API {
      * enum for parameter {{paramName}}
      */
     {{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}public{{/nonPublicApi}} enum {{enumName}}_{{operationId}}: {{^isContainer}}{{{dataType}}}{{/isContainer}}{{#isContainer}}String{{/isContainer}}, CaseIterable{{#useVapor}}, Content{{/useVapor}} {
+        {{^enumUnknownDefaultCase}}
         {{#allowableValues}}
         {{#enumVars}}
         case {{name}} = {{{value}}}
         {{/enumVars}}
         {{/allowableValues}}
+        {{/enumUnknownDefaultCase}}
+        {{#enumUnknownDefaultCase}}
+        {{#allowableValues}}
+        {{#enumVars}}
+        {{^-last}}
+        case {{name}} = {{{value}}}
+        {{/-last}}
+        {{/enumVars}}
+        {{/allowableValues}}
+        {{/enumUnknownDefaultCase}}
     }
     {{/isEnum}}
     {{/allParams}}
diff --git a/modules/openapi-generator/src/main/resources/swift5/modelEnum.mustache b/modules/openapi-generator/src/main/resources/swift5/modelEnum.mustache
index 08f7bf9ee40d..2b28d7c00810 100644
--- a/modules/openapi-generator/src/main/resources/swift5/modelEnum.mustache
+++ b/modules/openapi-generator/src/main/resources/swift5/modelEnum.mustache
@@ -1,32 +1,7 @@
-{{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}public{{/nonPublicApi}} enum {{classname}}: {{dataType}}, {{#useVapor}}Content, Hashable{{/useVapor}}{{^useVapor}}Codable{{/useVapor}}, CaseIterable{{^generateFrozenEnums}}{{#isInteger}}, CaseIterableDefaultsLast{{/isInteger}}{{#isFloat}}, CaseIterableDefaultsLast{{/isFloat}}{{#isDouble}}, CaseIterableDefaultsLast{{/isDouble}}{{#isString}}, CaseIterableDefaultsLast{{/isString}}{{/generateFrozenEnums}} {
+{{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}public{{/nonPublicApi}} enum {{classname}}: {{dataType}}, {{#useVapor}}Content, Hashable{{/useVapor}}{{^useVapor}}Codable{{/useVapor}}, CaseIterable{{#enumUnknownDefaultCase}}{{#isInteger}}, CaseIterableDefaultsLast{{/isInteger}}{{#isFloat}}, CaseIterableDefaultsLast{{/isFloat}}{{#isDouble}}, CaseIterableDefaultsLast{{/isDouble}}{{#isString}}, CaseIterableDefaultsLast{{/isString}}{{/enumUnknownDefaultCase}} {
 {{#allowableValues}}
 {{#enumVars}}
     case {{{name}}} = {{{value}}}
 {{/enumVars}}
 {{/allowableValues}}
-{{^generateFrozenEnums}}
-    // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-    // If new enum cases are added that are unknown to the spec/client, they are safely
-    // decoded to this case. The raw value of this case is a dummy value that attempts
-    // to avoids collisions with previously specified cases.
-{{#isString}}
-    case unknownDefaultOpenAPI = "unknown_default_open_api"
-{{/isString}}
-{{#isNumeric}}
-    //
-    // 192, used to calculate the raw value, was the Swift Evolution proposal for
-    // frozen/non-frozen enums.
-    // [SE-0192](https://github.com/apple/swift-evolution/blob/master/proposals/0192-non-exhaustive-enums.md)
-    //
-{{/isNumeric}}
-{{#isInteger}}
-    case unknownDefaultOpenAPI = -11184809 // Int.min / 192
-{{/isInteger}}
-{{#isDouble}}
-    case unknownDefaultOpenAPI = -11184809 // Int.min / 192
-{{/isDouble}}
-{{#isFloat}}
-    case unknownDefaultOpenAPI = -11184809 // Int.min / 192
-{{/isFloat}}
-{{/generateFrozenEnums}}
 }
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/swift5/modelInlineEnumDeclaration.mustache b/modules/openapi-generator/src/main/resources/swift5/modelInlineEnumDeclaration.mustache
index 1dd9c55b16fd..445f56873884 100644
--- a/modules/openapi-generator/src/main/resources/swift5/modelInlineEnumDeclaration.mustache
+++ b/modules/openapi-generator/src/main/resources/swift5/modelInlineEnumDeclaration.mustache
@@ -1,35 +1,7 @@
-    {{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}public{{/nonPublicApi}} enum {{enumName}}: {{^isContainer}}{{dataType}}{{/isContainer}}{{#isContainer}}String{{/isContainer}}, {{#useVapor}}Content, Hashable{{/useVapor}}{{^useVapor}}Codable{{/useVapor}}, CaseIterable{{^generateFrozenEnums}}{{#isInteger}}, CaseIterableDefaultsLast{{/isInteger}}{{#isFloat}}, CaseIterableDefaultsLast{{/isFloat}}{{#isDouble}}, CaseIterableDefaultsLast{{/isDouble}}{{#isString}}, CaseIterableDefaultsLast{{/isString}}{{#isContainer}}, CaseIterableDefaultsLast{{/isContainer}}{{/generateFrozenEnums}} {
+    {{#nonPublicApi}}internal{{/nonPublicApi}}{{^nonPublicApi}}public{{/nonPublicApi}} enum {{enumName}}: {{^isContainer}}{{dataType}}{{/isContainer}}{{#isContainer}}String{{/isContainer}}, {{#useVapor}}Content, Hashable{{/useVapor}}{{^useVapor}}Codable{{/useVapor}}, CaseIterable{{#enumUnknownDefaultCase}}{{#isInteger}}, CaseIterableDefaultsLast{{/isInteger}}{{#isFloat}}, CaseIterableDefaultsLast{{/isFloat}}{{#isDouble}}, CaseIterableDefaultsLast{{/isDouble}}{{#isString}}, CaseIterableDefaultsLast{{/isString}}{{#isContainer}}, CaseIterableDefaultsLast{{/isContainer}}{{/enumUnknownDefaultCase}} {
         {{#allowableValues}}
         {{#enumVars}}
         case {{{name}}} = {{{value}}}
         {{/enumVars}}
         {{/allowableValues}}
-        {{^generateFrozenEnums}}
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        {{#isString}}
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
-        {{/isString}}
-        {{#isContainer}}
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
-        {{/isContainer}}
-        {{#isNumeric}}
-        //
-        // 192, used to calculate the raw value, was the Swift Evolution proposal for
-        // frozen/non-frozen enums.
-        // [SE-0192](https://github.com/apple/swift-evolution/blob/master/proposals/0192-non-exhaustive-enums.md)
-        //
-        {{/isNumeric}}
-        {{#isInteger}}
-        case unknownDefaultOpenAPI = -11184809 // Int.min / 192
-        {{/isInteger}}
-        {{#isDouble}}
-        case unknownDefaultOpenAPI = -11184809 // Int.min / 192
-        {{/isDouble}}
-        {{#isFloat}}
-        case unknownDefaultOpenAPI = -11184809 // Int.min / 192
-        {{/isFloat}}
-        {{/generateFrozenEnums}}
     }
\ No newline at end of file
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/bash/BashClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/bash/BashClientOptionsTest.java
index 1d08eab2bede..11b557d2ae46 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/bash/BashClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/bash/BashClientOptionsTest.java
@@ -58,6 +58,7 @@ protected void verifyOptions() {
         verify(clientCodegen).setApiKeyAuthEnvironmentVariable(
                 BashClientOptionsProvider.APIKEY_AUTH_ENVIRONMENT_VARIABLE_NAME);
         verify(clientCodegen).setAllowUnicodeIdentifiers(Boolean.valueOf(BashClientOptionsProvider.ALLOW_UNICODE_IDENTIFIERS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(BashClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/DartClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/DartClientOptionsTest.java
index 62693bf85447..1b268561e52a 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/DartClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/DartClientOptionsTest.java
@@ -50,5 +50,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setPubHomepage(DartClientOptionsProvider.PUB_HOMEPAGE_VALUE);
         verify(clientCodegen).setSourceFolder(DartClientOptionsProvider.SOURCE_FOLDER_VALUE);
         verify(clientCodegen).setUseEnumExtension(Boolean.parseBoolean(DartClientOptionsProvider.USE_ENUM_EXTENSION));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(DartClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioClientOptionsTest.java
index 478d243580e4..9008b713bb00 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioClientOptionsTest.java
@@ -52,5 +52,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setUseEnumExtension(Boolean.parseBoolean(DartDioClientOptionsProvider.USE_ENUM_EXTENSION));
         verify(clientCodegen).setDateLibrary(DartDioClientOptionsProvider.DATE_LIBRARY);
         verify(clientCodegen).setNullableFields(Boolean.parseBoolean(DartDioClientOptionsProvider.NULLABLE_FIELDS));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(DartDioClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioNextClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioNextClientOptionsTest.java
index f2237e4fbaaa..61c386b274a5 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioNextClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/dart/dio/DartDioNextClientOptionsTest.java
@@ -51,5 +51,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setUseEnumExtension(Boolean.parseBoolean(DartDioNextClientOptionsProvider.USE_ENUM_EXTENSION));
         verify(clientCodegen).setDateLibrary(DartDioNextClientCodegen.DATE_LIBRARY_DEFAULT);
         verify(clientCodegen).setLibrary(DartDioNextClientCodegen.SERIALIZATION_LIBRARY_DEFAULT);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(DartDioNextClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/elixir/ElixirClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/elixir/ElixirClientOptionsTest.java
index 41fe7cbbbbf5..a969cc174103 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/elixir/ElixirClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/elixir/ElixirClientOptionsTest.java
@@ -42,5 +42,6 @@ protected CodegenConfig getCodegenConfig() {
     @Override
     protected void verifyOptions() {
         verify(clientCodegen).setModuleName(ElixirClientOptionsProvider.INVOKER_PACKAGE_VALUE);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(ElixirClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
\ No newline at end of file
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/haskellservant/HaskellServantOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/haskellservant/HaskellServantOptionsTest.java
index 769dcbedbd60..40d4cbba4329 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/haskellservant/HaskellServantOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/haskellservant/HaskellServantOptionsTest.java
@@ -43,5 +43,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setModelPackage(HaskellServantOptionsProvider.MODEL_PACKAGE_VALUE);
         verify(clientCodegen).setApiPackage(HaskellServantOptionsProvider.API_PACKAGE_VALUE);
         verify(clientCodegen).setSortParamsByRequiredFlag(Boolean.valueOf(HaskellServantOptionsProvider.SORT_PARAMS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(HaskellServantOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/haskellyesod/HaskellYesodServerOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/haskellyesod/HaskellYesodServerOptionsTest.java
index 07d317b23daa..128b10a086c5 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/haskellyesod/HaskellYesodServerOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/haskellyesod/HaskellYesodServerOptionsTest.java
@@ -25,5 +25,6 @@ protected CodegenConfig getCodegenConfig() {
     protected void verifyOptions() {
         verify(clientCodegen).setProjectName(HaskellYesodServerOptionsProvider.PROJECT_NAME_VALUE);
         verify(clientCodegen).setApiModuleName(HaskellYesodServerOptionsProvider.API_MODULE_NAME_VALUE);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(HaskellYesodServerOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/lumen/PhpLumenServerOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/lumen/PhpLumenServerOptionsTest.java
index 4a79464569b5..73af635bb02a 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/lumen/PhpLumenServerOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/lumen/PhpLumenServerOptionsTest.java
@@ -48,5 +48,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setPackageName(PhpLumenServerOptionsProvider.PACKAGE_NAME_VALUE);
         verify(clientCodegen).setSrcBasePath(PhpLumenServerOptionsProvider.SRC_BASE_PATH_VALUE);
         verify(clientCodegen).setArtifactVersion(PhpLumenServerOptionsProvider.ARTIFACT_VERSION_VALUE);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(PhpLumenServerOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/BashClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/BashClientOptionsProvider.java
index b2c8415fdca0..338a9e5ea13a 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/BashClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/BashClientOptionsProvider.java
@@ -39,6 +39,7 @@ public class BashClientOptionsProvider implements OptionsProvider {
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE
                                 = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -72,6 +73,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
 
     }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartClientOptionsProvider.java
index 464560449f01..5e468090bed6 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartClientOptionsProvider.java
@@ -39,6 +39,7 @@ public class DartClientOptionsProvider implements OptionsProvider {
     public static final String USE_ENUM_EXTENSION = "true";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -65,6 +66,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
                 .put("serializationLibrary", "custom")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartDioClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartDioClientOptionsProvider.java
index fa6bb3eeadb1..e974ddd8494c 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartDioClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartDioClientOptionsProvider.java
@@ -41,6 +41,7 @@ public class DartDioClientOptionsProvider implements OptionsProvider {
     public static final String PUB_AUTHOR_VALUE = "Author";
     public static final String PUB_AUTHOR_EMAIL_VALUE = "author@homepage";
     public static final String PUB_HOMEPAGE_VALUE = "Homepage";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -68,6 +69,7 @@ public Map<String, String> createOptions() {
                 .put(DartDioClientCodegen.NULLABLE_FIELDS, NULLABLE_FIELDS)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartDioNextClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartDioNextClientOptionsProvider.java
index b03f2a972142..cda6e36cfc6c 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartDioNextClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/DartDioNextClientOptionsProvider.java
@@ -37,6 +37,7 @@ public class DartDioNextClientOptionsProvider implements OptionsProvider {
     public static final String PUB_AUTHOR_VALUE = "Author";
     public static final String PUB_AUTHOR_EMAIL_VALUE = "author@homepage";
     public static final String PUB_HOMEPAGE_VALUE = "Homepage";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -64,6 +65,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ElixirClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ElixirClientOptionsProvider.java
index bd39161584fd..32b7b3d34151 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ElixirClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ElixirClientOptionsProvider.java
@@ -25,6 +25,7 @@
 public class ElixirClientOptionsProvider implements OptionsProvider {
     public static final String INVOKER_PACKAGE_VALUE = "Yay.Pets";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -45,6 +46,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/HaskellServantOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/HaskellServantOptionsProvider.java
index 728b44ef38fe..892a753ce90f 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/HaskellServantOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/HaskellServantOptionsProvider.java
@@ -31,6 +31,7 @@ public class HaskellServantOptionsProvider implements OptionsProvider {
     public static final String ENSURE_UNIQUE_PARAMS_VALUE = "true";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -50,6 +51,7 @@ public Map<String, String> createOptions() {
                 .put(HaskellServantCodegen.PROP_SERVE_STATIC, HaskellServantCodegen.PROP_SERVE_STATIC_DEFAULT.toString())
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/HaskellYesodServerOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/HaskellYesodServerOptionsProvider.java
index 230c2243a803..66fd08f19aaa 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/HaskellYesodServerOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/HaskellYesodServerOptionsProvider.java
@@ -14,6 +14,7 @@ public class HaskellYesodServerOptionsProvider implements OptionsProvider {
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
     public static final String PROJECT_NAME_VALUE = "openapi-haskell-yesod-server";
     public static final String API_MODULE_NAME_VALUE = "API";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -32,6 +33,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
                 .put(HaskellYesodServerCodegen.PROJECT_NAME, PROJECT_NAME_VALUE)
                 .put(HaskellYesodServerCodegen.API_MODULE_NAME, API_MODULE_NAME_VALUE)
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpClientOptionsProvider.java
index b2a987d924ea..21ce7e748c84 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpClientOptionsProvider.java
@@ -36,6 +36,7 @@ public class PhpClientOptionsProvider implements OptionsProvider {
     public static final String ARTIFACT_VERSION_VALUE = "1.0.0-SNAPSHOT";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -60,6 +61,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpLumenServerOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpLumenServerOptionsProvider.java
index 25d34b16d80a..3c0779cf5f87 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpLumenServerOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpLumenServerOptionsProvider.java
@@ -36,6 +36,7 @@ public class PhpLumenServerOptionsProvider implements OptionsProvider {
     public static final String ARTIFACT_VERSION_VALUE = "1.0.0-SNAPSHOT";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -59,6 +60,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSilexServerOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSilexServerOptionsProvider.java
index b6c55c7a27b2..900aab03c7bf 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSilexServerOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSilexServerOptionsProvider.java
@@ -28,6 +28,7 @@ public class PhpSilexServerOptionsProvider implements OptionsProvider {
     public static final String ENSURE_UNIQUE_PARAMS_VALUE = "true";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -44,6 +45,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSlim4ServerOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSlim4ServerOptionsProvider.java
index 3295ed951011..2e6a8f6ee665 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSlim4ServerOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSlim4ServerOptionsProvider.java
@@ -38,6 +38,7 @@ public class PhpSlim4ServerOptionsProvider implements OptionsProvider {
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
     public static final String PSR7_IMPLEMENTATION_VALUE = "zend-diactoros";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -62,6 +63,7 @@ public Map<String, String> createOptions() {
                 .put(PhpSlim4ServerCodegen.PSR7_IMPLEMENTATION, PSR7_IMPLEMENTATION_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSlimServerOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSlimServerOptionsProvider.java
index 4a40588c0ebb..be1d495713f7 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSlimServerOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/PhpSlimServerOptionsProvider.java
@@ -36,6 +36,7 @@ public class PhpSlimServerOptionsProvider implements OptionsProvider {
     public static final String ENSURE_UNIQUE_PARAMS_VALUE = "true";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -59,6 +60,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/RubyClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/RubyClientOptionsProvider.java
index 9d5c63f9d2da..807c0035bda7 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/RubyClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/RubyClientOptionsProvider.java
@@ -40,6 +40,7 @@ public class RubyClientOptionsProvider implements OptionsProvider {
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
     public static final String LIBRARY = "typhoeus";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -68,6 +69,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.LIBRARY, LIBRARY)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ScalaAkkaClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ScalaAkkaClientOptionsProvider.java
index 62909fb5b3f2..7c4e5d4a1b92 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ScalaAkkaClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ScalaAkkaClientOptionsProvider.java
@@ -34,6 +34,7 @@ public class ScalaAkkaClientOptionsProvider implements OptionsProvider {
     public static final String MAIN_PACKAGE_VALUE = "net.test";
     public static final String MODEL_PROPERTY_NAMING = "camelCase";
     public static final String DATE_LIBRARY = "joda";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
 
     @Override
@@ -57,6 +58,7 @@ public Map<String, String> createOptions() {
                 .put("dateLibrary", DATE_LIBRARY)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ScalaHttpClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ScalaHttpClientOptionsProvider.java
index ac3c7f713c55..c8c56053cf0c 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ScalaHttpClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/ScalaHttpClientOptionsProvider.java
@@ -33,6 +33,7 @@ public class ScalaHttpClientOptionsProvider implements OptionsProvider {
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
     public static final String DATE_LIBRARY = "joda";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -54,6 +55,7 @@ public Map<String, String> createOptions() {
                 .put("dateLibrary", DATE_LIBRARY)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/Swift4OptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/Swift4OptionsProvider.java
deleted file mode 100644
index 038c40121d62..000000000000
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/Swift4OptionsProvider.java
+++ /dev/null
@@ -1,93 +0,0 @@
-/*
- * Copyright 2018 OpenAPI-Generator Contributors (https://openapi-generator.tech)
- * Copyright 2018 SmartBear Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.openapitools.codegen.options;
-
-import com.google.common.collect.ImmutableMap;
-import org.openapitools.codegen.CodegenConstants;
-import org.openapitools.codegen.languages.Swift4Codegen;
-
-import java.util.Map;
-
-public class Swift4OptionsProvider implements OptionsProvider {
-    public static final String SORT_PARAMS_VALUE = "false";
-    public static final String SORT_MODEL_PROPERTIES_VALUE = "false";
-    public static final String ENSURE_UNIQUE_PARAMS_VALUE = "true";
-    public static final String PROJECT_NAME_VALUE = "Swagger";
-    public static final String RESPONSE_AS_VALUE = "test";
-    public static final String NON_PUBLIC_API_REQUIRED_VALUE = "false";
-    public static final String UNWRAP_REQUIRED_VALUE = "true";
-    public static final String OBJC_COMPATIBLE_VALUE = "false";
-    public static final String LENIENT_TYPE_CAST_VALUE = "false";
-    public static final String POD_SOURCE_VALUE = "{ :git => 'git@github.com:swagger-api/swagger-mustache.git'," +
-            " :tag => 'v1.0.0-SNAPSHOT' }";
-    public static final String POD_VERSION_VALUE = "v1.0.0-SNAPSHOT";
-    public static final String POD_AUTHORS_VALUE = "podAuthors";
-    public static final String POD_SOCIAL_MEDIA_URL_VALUE = "podSocialMediaURL";
-    public static final String POD_DOCSET_URL_VALUE = "podDocsetURL";
-    public static final String POD_LICENSE_VALUE = "'Apache License, Version 2.0'";
-    public static final String POD_HOMEPAGE_VALUE = "podHomepage";
-    public static final String POD_SUMMARY_VALUE = "podSummary";
-    public static final String POD_DESCRIPTION_VALUE = "podDescription";
-    public static final String POD_SCREENSHOTS_VALUE = "podScreenshots";
-    public static final String POD_DOCUMENTATION_URL_VALUE = "podDocumentationURL";
-    public static final String SWIFT_USE_API_NAMESPACE_VALUE = "swiftUseApiNamespace";
-    public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
-    public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
-
-    @Override
-    public String getLanguage() {
-        return "swift4";
-    }
-
-    @Override
-    public Map<String, String> createOptions() {
-        ImmutableMap.Builder<String, String> builder = new ImmutableMap.Builder<String, String>();
-        return builder.put(CodegenConstants.SORT_PARAMS_BY_REQUIRED_FLAG, SORT_PARAMS_VALUE)
-                .put(CodegenConstants.SORT_MODEL_PROPERTIES_BY_REQUIRED_FLAG, SORT_MODEL_PROPERTIES_VALUE)
-                .put(CodegenConstants.ENSURE_UNIQUE_PARAMS, ENSURE_UNIQUE_PARAMS_VALUE)
-                .put(Swift4Codegen.PROJECT_NAME, PROJECT_NAME_VALUE)
-                .put(Swift4Codegen.RESPONSE_AS, RESPONSE_AS_VALUE)
-                .put(CodegenConstants.NON_PUBLIC_API, NON_PUBLIC_API_REQUIRED_VALUE)
-                .put(Swift4Codegen.UNWRAP_REQUIRED, UNWRAP_REQUIRED_VALUE)
-                .put(Swift4Codegen.OBJC_COMPATIBLE, OBJC_COMPATIBLE_VALUE)
-                .put(Swift4Codegen.LENIENT_TYPE_CAST, LENIENT_TYPE_CAST_VALUE)
-                .put(Swift4Codegen.POD_SOURCE, POD_SOURCE_VALUE)
-                .put(CodegenConstants.POD_VERSION, POD_VERSION_VALUE)
-                .put(Swift4Codegen.POD_AUTHORS, POD_AUTHORS_VALUE)
-                .put(Swift4Codegen.POD_SOCIAL_MEDIA_URL, POD_SOCIAL_MEDIA_URL_VALUE)
-                .put(Swift4Codegen.POD_DOCSET_URL, POD_DOCSET_URL_VALUE)
-                .put(Swift4Codegen.POD_LICENSE, POD_LICENSE_VALUE)
-                .put(Swift4Codegen.POD_HOMEPAGE, POD_HOMEPAGE_VALUE)
-                .put(Swift4Codegen.POD_SUMMARY, POD_SUMMARY_VALUE)
-                .put(Swift4Codegen.POD_DESCRIPTION, POD_DESCRIPTION_VALUE)
-                .put(Swift4Codegen.POD_SCREENSHOTS, POD_SCREENSHOTS_VALUE)
-                .put(Swift4Codegen.POD_DOCUMENTATION_URL, POD_DOCUMENTATION_URL_VALUE)
-                .put(Swift4Codegen.SWIFT_USE_API_NAMESPACE, SWIFT_USE_API_NAMESPACE_VALUE)
-                .put(CodegenConstants.HIDE_GENERATION_TIMESTAMP, "true")
-                .put(CodegenConstants.ALLOW_UNICODE_IDENTIFIERS, ALLOW_UNICODE_IDENTIFIERS_VALUE)
-                .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
-                .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
-                .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
-                .build();
-    }
-
-    @Override
-    public boolean isServer() {
-        return false;
-    }
-}
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/Swift5OptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/Swift5OptionsProvider.java
index 4df5b89d5ba7..003e5b4b5b7d 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/Swift5OptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/Swift5OptionsProvider.java
@@ -48,7 +48,6 @@ public class Swift5OptionsProvider implements OptionsProvider {
     public static final String REMOVE_MIGRATION_PROJECT_NAME_CLASS_VALUE = "false";
     public static final String SWIFT_USE_API_NAMESPACE_VALUE = "swiftUseApiNamespace";
     public static final String USE_BACKTICKS_ESCAPES_VALUE = "false";
-    public static final String GENERATE_FROZEN_ENUMS_VALUE = "true";
     public static final String GENERATE_MODEL_ADDITIONAL_PROPERTIES_VALUE = "true";
     public static final String HASHABLE_MODELS_VALUE = "true";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
@@ -56,6 +55,7 @@ public class Swift5OptionsProvider implements OptionsProvider {
     public static final String LIBRARY_VALUE = "alamofire";
     public static final String USE_SPM_FILE_STRUCTURE_VALUE = "false";
     public static final String SWIFT_PACKAGE_PATH_VALUE = "";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -96,11 +96,11 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
                 .put(Swift5ClientCodegen.USE_SPM_FILE_STRUCTURE, USE_SPM_FILE_STRUCTURE_VALUE)
                 .put(Swift5ClientCodegen.SWIFT_PACKAGE_PATH, SWIFT_PACKAGE_PATH_VALUE)
-                .put(Swift5ClientCodegen.GENERATE_FROZEN_ENUMS, GENERATE_FROZEN_ENUMS_VALUE)
                 .put(Swift5ClientCodegen.GENERATE_MODEL_ADDITIONAL_PROPERTIES, GENERATE_MODEL_ADDITIONAL_PROPERTIES_VALUE)
                 .put(Swift5ClientCodegen.HASHABLE_MODELS, HASHABLE_MODELS_VALUE)
                 .put(Swift5ClientCodegen.MAP_FILE_BINARY_TO_DATA, "false")
                 .put(Swift5ClientCodegen.USE_CLASSES, "false")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAngularClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAngularClientOptionsProvider.java
index aa67286b9786..b3d82668ecbf 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAngularClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAngularClientOptionsProvider.java
@@ -50,6 +50,7 @@ public class TypeScriptAngularClientOptionsProvider implements OptionsProvider {
     public static String SERVICE_FILE_SUFFIX = ".service";
     public static String MODEL_SUFFIX = "";
     public static String MODEL_FILE_SUFFIX = "";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -91,6 +92,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
                 .put(TypeScriptAngularClientCodegen.QUERY_PARAM_OBJECT_FORMAT, QUERY_PARAM_OBJECT_FORMAT_VALUE)
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAngularJsClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAngularJsClientOptionsProvider.java
index 1b9c8a58e174..fd62de4e03b8 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAngularJsClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAngularJsClientOptionsProvider.java
@@ -35,6 +35,7 @@ public class TypeScriptAngularJsClientOptionsProvider implements OptionsProvider
     public static final String ENUM_PROPERTY_NAMING_VALUE = "PascalCase";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -57,6 +58,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAureliaClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAureliaClientOptionsProvider.java
index 939a0fad979b..7cc5631fecbe 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAureliaClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptAureliaClientOptionsProvider.java
@@ -38,6 +38,7 @@ public class TypeScriptAureliaClientOptionsProvider implements OptionsProvider {
     private static final String NPM_VERSION = "1.0.0";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -63,6 +64,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptFetchClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptFetchClientOptionsProvider.java
index f33f1c437d64..5c2fb91f7255 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptFetchClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptFetchClientOptionsProvider.java
@@ -42,6 +42,7 @@ public class TypeScriptFetchClientOptionsProvider implements OptionsProvider {
     public static final String TYPESCRIPT_THREE_PLUS = "true";
     public static final String WITHOUT_RUNTIME_CHECKS = "true";
     public static final String SAGAS_AND_RECORDS = "false";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -74,6 +75,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptNestjsClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptNestjsClientOptionsProvider.java
index d86f586e15c3..d7143efcfc30 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptNestjsClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptNestjsClientOptionsProvider.java
@@ -46,6 +46,7 @@ public class TypeScriptNestjsClientOptionsProvider implements OptionsProvider {
     public static String SERVICE_FILE_SUFFIX = ".service";
     public static String MODEL_SUFFIX = "";
     public static String MODEL_FILE_SUFFIX = "";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -84,6 +85,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
                 .put(TypeScriptNestjsClientCodegen.FILE_NAMING, FILE_NAMING_VALUE)
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptNodeClientOptionsProvider.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptNodeClientOptionsProvider.java
index fb2b6a741dc5..a82306a54201 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptNodeClientOptionsProvider.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/options/TypeScriptNodeClientOptionsProvider.java
@@ -41,6 +41,7 @@ public class TypeScriptNodeClientOptionsProvider implements OptionsProvider {
     public static final String API_SUFFIX = "Api";
     public static final String ALLOW_UNICODE_IDENTIFIERS_VALUE = "false";
     public static final String PREPEND_FORM_OR_BODY_PARAMETERS_VALUE = "true";
+    public static final String ENUM_UNKNOWN_DEFAULT_CASE_VALUE = "false";
 
     @Override
     public String getLanguage() {
@@ -67,6 +68,7 @@ public Map<String, String> createOptions() {
                 .put(CodegenConstants.PREPEND_FORM_OR_BODY_PARAMETERS, PREPEND_FORM_OR_BODY_PARAMETERS_VALUE)
                 .put(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "true")
                 .put(CodegenConstants.DISALLOW_ADDITIONAL_PROPERTIES_IF_NOT_PRESENT, "true")
+                .put(CodegenConstants.ENUM_UNKNOWN_DEFAULT_CASE, ENUM_UNKNOWN_DEFAULT_CASE_VALUE)
                 .build();
     }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/php/PhpClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/php/PhpClientOptionsTest.java
index 8479c3441a42..0432dec115e8 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/php/PhpClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/php/PhpClientOptionsTest.java
@@ -48,5 +48,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setPackageName(PhpClientOptionsProvider.PACKAGE_NAME_VALUE);
         verify(clientCodegen).setSrcBasePath(PhpClientOptionsProvider.SRC_BASE_PATH_VALUE);
         verify(clientCodegen).setArtifactVersion(PhpClientOptionsProvider.ARTIFACT_VERSION_VALUE);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(PhpClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientOptionsTest.java
index 6c338ad66b5f..c44d3d9b1a94 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/ruby/RubyClientOptionsTest.java
@@ -50,5 +50,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setGemSummary(RubyClientOptionsProvider.GEM_SUMMARY_VALUE);
         verify(clientCodegen).setGemAuthor(RubyClientOptionsProvider.GEM_AUTHOR_VALUE);
         verify(clientCodegen).setGemAuthorEmail(RubyClientOptionsProvider.GEM_AUTHOR_EMAIL_VALUE);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(RubyClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalaakka/ScalaAkkaClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalaakka/ScalaAkkaClientOptionsTest.java
index fbb919e9fa54..fbcece61d96d 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalaakka/ScalaAkkaClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalaakka/ScalaAkkaClientOptionsTest.java
@@ -47,5 +47,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(ScalaAkkaClientOptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
         verify(clientCodegen).setMainPackage(ScalaAkkaClientOptionsProvider.MAIN_PACKAGE_VALUE);
         verify(clientCodegen).setModelPropertyNaming(ScalaAkkaClientOptionsProvider.MODEL_PROPERTY_NAMING);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(ScalaAkkaClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalahttpclient/ScalaHttpClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalahttpclient/ScalaHttpClientOptionsTest.java
index a70da4206bc3..33692fab6009 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalahttpclient/ScalaHttpClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/scalahttpclient/ScalaHttpClientOptionsTest.java
@@ -48,5 +48,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setSourceFolder(ScalaHttpClientOptionsProvider.SOURCE_FOLDER_VALUE);
         verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(ScalaHttpClientOptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
         verify(clientCodegen).setDateLibrary(ScalaHttpClientOptionsProvider.DATE_LIBRARY,false);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(ScalaHttpClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/silex/PhpSilexServerOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/silex/PhpSilexServerOptionsTest.java
index d7dcc1a28014..9ea6f43e43a1 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/silex/PhpSilexServerOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/silex/PhpSilexServerOptionsTest.java
@@ -41,5 +41,6 @@ protected CodegenConfig getCodegenConfig() {
     @Override
     protected void verifyOptions() {
         verify(clientCodegen).setSortParamsByRequiredFlag(Boolean.valueOf(PhpSilexServerOptionsProvider.SORT_PARAMS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(PhpSilexServerOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/slim/PhpSlimServerOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/slim/PhpSlimServerOptionsTest.java
index ad6fb48b273d..e436efed1a33 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/slim/PhpSlimServerOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/slim/PhpSlimServerOptionsTest.java
@@ -48,5 +48,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setSrcBasePath(PhpSlimServerOptionsProvider.SRC_BASE_PATH_VALUE);
         verify(clientCodegen).setArtifactVersion(PhpSlimServerOptionsProvider.ARTIFACT_VERSION_VALUE);
         verify(clientCodegen).setSortParamsByRequiredFlag(Boolean.valueOf(PhpSlimServerOptionsProvider.SORT_PARAMS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(PhpSlimServerOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/slim4/PhpSlim4ServerOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/slim4/PhpSlim4ServerOptionsTest.java
index 499e6bec639c..b9c76e6b6414 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/slim4/PhpSlim4ServerOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/slim4/PhpSlim4ServerOptionsTest.java
@@ -49,6 +49,7 @@ protected void verifyOptions() {
         verify(clientCodegen).setArtifactVersion(PhpSlim4ServerOptionsProvider.ARTIFACT_VERSION_VALUE);
         verify(clientCodegen).setSortParamsByRequiredFlag(Boolean.valueOf(PhpSlim4ServerOptionsProvider.SORT_PARAMS_VALUE));
         verify(clientCodegen).setPsr7Implementation(PhpSlim4ServerOptionsProvider.PSR7_IMPLEMENTATION_VALUE);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(PhpSlim4ServerOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
 
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4CodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4CodegenTest.java
deleted file mode 100644
index aeef2b73edbc..000000000000
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4CodegenTest.java
+++ /dev/null
@@ -1,147 +0,0 @@
-/*
- * Copyright 2018 OpenAPI-Generator Contributors (https://openapi-generator.tech)
- * Copyright 2018 SmartBear Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.openapitools.codegen.swift4;
-
-import io.swagger.v3.oas.models.OpenAPI;
-import io.swagger.v3.oas.models.Operation;
-import org.openapitools.codegen.CodegenOperation;
-import org.openapitools.codegen.DefaultCodegen;
-import org.openapitools.codegen.TestUtils;
-import org.openapitools.codegen.languages.Swift4Codegen;
-import org.testng.Assert;
-import org.testng.annotations.Test;
-
-
-public class Swift4CodegenTest {
-
-    Swift4Codegen swiftCodegen = new Swift4Codegen();
-
-    @Test(enabled = true)
-    public void testCapitalizedReservedWord() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("AS", null), "_as");
-    }
-
-    @Test(enabled = true)
-    public void testReservedWord() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("Public", null), "_public");
-    }
-
-    @Test(enabled = true)
-    public void shouldNotBreakNonReservedWord() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("Error", null), "error");
-    }
-
-    @Test(enabled = true)
-    public void shouldNotBreakCorrectName() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("EntryName", null), "entryName");
-    }
-
-    @Test(enabled = true)
-    public void testSingleWordAllCaps() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("VALUE", null), "value");
-    }
-
-    @Test(enabled = true)
-    public void testSingleWordLowercase() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("value", null), "value");
-    }
-
-    @Test(enabled = true)
-    public void testCapitalsWithUnderscore() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("ENTRY_NAME", null), "entryName");
-    }
-
-    @Test(enabled = true)
-    public void testCapitalsWithDash() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("ENTRY-NAME", null), "entryName");
-    }
-
-    @Test(enabled = true)
-    public void testCapitalsWithSpace() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("ENTRY NAME", null), "entryName");
-    }
-
-    @Test(enabled = true)
-    public void testLowercaseWithUnderscore() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("entry_name", null), "entryName");
-    }
-
-    @Test(enabled = true)
-    public void testStartingWithNumber() throws Exception {
-        Assert.assertEquals(swiftCodegen.toEnumVarName("123EntryName", null), "_123entryName");
-        Assert.assertEquals(swiftCodegen.toEnumVarName("123Entry_name", null), "_123entryName");
-        Assert.assertEquals(swiftCodegen.toEnumVarName("123EntryName123", null), "_123entryName123");
-    }
-
-    @Test(description = "returns Data when response format is binary", enabled = true)
-    public void binaryDataTest() {
-        // TODO update json file
-
-        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/2_0/binaryDataTest.json");
-        final DefaultCodegen codegen = new Swift4Codegen();
-        codegen.setOpenAPI(openAPI);
-        final String path = "/tests/binaryResponse";
-        final Operation p = openAPI.getPaths().get(path).getPost();
-        final CodegenOperation op = codegen.fromOperation(path, "post", p, null);
-
-        Assert.assertEquals(op.returnType, "URL");
-        Assert.assertEquals(op.bodyParam.dataType, "URL");
-        Assert.assertTrue(op.bodyParam.isBinary);
-        Assert.assertTrue(op.responses.get(0).isBinary);
-    }
-
-    @Test(description = "returns Date when response format is date", enabled = true)
-    public void dateTest() {
-        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/2_0/datePropertyTest.json");
-        final DefaultCodegen codegen = new Swift4Codegen();
-        codegen.setOpenAPI(openAPI);
-        final String path = "/tests/dateResponse";
-        final Operation p = openAPI.getPaths().get(path).getPost();
-        final CodegenOperation op = codegen.fromOperation(path, "post", p, null);
-
-        Assert.assertEquals(op.returnType, "Date");
-        Assert.assertEquals(op.bodyParam.dataType, "Date");
-    }
-
-    @Test(enabled = true)
-    public void testDefaultPodAuthors() throws Exception {
-        // Given
-
-        // When
-        swiftCodegen.processOpts();
-
-        // Then
-        final String podAuthors = (String) swiftCodegen.additionalProperties().get(Swift4Codegen.POD_AUTHORS);
-        Assert.assertEquals(podAuthors, Swift4Codegen.DEFAULT_POD_AUTHORS);
-    }
-
-    @Test(enabled = true)
-    public void testPodAuthors() throws Exception {
-        // Given
-        final String openAPIDevs = "OpenAPI Devs";
-        swiftCodegen.additionalProperties().put(Swift4Codegen.POD_AUTHORS, openAPIDevs);
-
-        // When
-        swiftCodegen.processOpts();
-
-        // Then
-        final String podAuthors = (String) swiftCodegen.additionalProperties().get(Swift4Codegen.POD_AUTHORS);
-        Assert.assertEquals(podAuthors, openAPIDevs);
-    }
-
-}
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4ModelEnumTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4ModelEnumTest.java
deleted file mode 100644
index 2b7696ba532f..000000000000
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4ModelEnumTest.java
+++ /dev/null
@@ -1,133 +0,0 @@
-/*
- * Copyright 2018 OpenAPI-Generator Contributors (https://openapi-generator.tech)
- * Copyright 2018 SmartBear Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.openapitools.codegen.swift4;
-
-import io.swagger.v3.oas.models.OpenAPI;
-import io.swagger.v3.oas.models.media.IntegerSchema;
-import io.swagger.v3.oas.models.media.NumberSchema;
-import io.swagger.v3.oas.models.media.Schema;
-import io.swagger.v3.oas.models.media.StringSchema;
-import org.openapitools.codegen.CodegenModel;
-import org.openapitools.codegen.CodegenProperty;
-import org.openapitools.codegen.DefaultCodegen;
-import org.openapitools.codegen.TestUtils;
-import org.openapitools.codegen.languages.Swift4Codegen;
-import org.testng.Assert;
-import org.testng.annotations.Test;
-
-import java.math.BigDecimal;
-import java.util.Arrays;
-
-@SuppressWarnings("static-method")
-public class Swift4ModelEnumTest {
-    @Test(description = "convert a java model with an string enum and a default value")
-    public void convertStringDefaultValueTest() {
-        final StringSchema enumSchema = new StringSchema();
-        enumSchema.setEnum(Arrays.asList("VALUE1", "VALUE2", "VALUE3"));
-        enumSchema.setDefault("VALUE2");
-        final Schema model = new Schema().type("object").addProperties("name", enumSchema);
-
-        final DefaultCodegen codegen = new Swift4Codegen();
-        OpenAPI openAPI = TestUtils.createOpenAPIWithOneSchema("sample", model);
-        codegen.setOpenAPI(openAPI);
-        final CodegenModel cm = codegen.fromModel("sample", model);
-
-        Assert.assertEquals(cm.vars.size(), 1);
-
-        final CodegenProperty enumVar = cm.vars.get(0);
-        Assert.assertEquals(enumVar.baseName, "name");
-        Assert.assertEquals(enumVar.dataType, "String");
-        Assert.assertEquals(enumVar.datatypeWithEnum, "Name");
-        Assert.assertEquals(enumVar.name, "name");
-        Assert.assertEquals(enumVar.defaultValue, ".value2");
-        Assert.assertEquals(enumVar.baseType, "String");
-        Assert.assertTrue(enumVar.isEnum);
-    }
-
-    @Test(description = "convert a java model with an reserved word string enum and a default value")
-    public void convertReservedWordStringDefaultValueTest() {
-        final StringSchema enumSchema = new StringSchema();
-        enumSchema.setEnum(Arrays.asList("1st", "2nd", "3rd"));
-        enumSchema.setDefault("2nd");
-        final Schema model = new Schema().type("object").addProperties("name", enumSchema);
-
-        final DefaultCodegen codegen = new Swift4Codegen();
-        OpenAPI openAPI = TestUtils.createOpenAPIWithOneSchema("sample", model);
-        codegen.setOpenAPI(openAPI);
-        final CodegenModel cm = codegen.fromModel("sample", model);
-
-        Assert.assertEquals(cm.vars.size(), 1);
-
-        final CodegenProperty enumVar = cm.vars.get(0);
-        Assert.assertEquals(enumVar.baseName, "name");
-        Assert.assertEquals(enumVar.dataType, "String");
-        Assert.assertEquals(enumVar.datatypeWithEnum, "Name");
-        Assert.assertEquals(enumVar.name, "name");
-        Assert.assertEquals(enumVar.defaultValue, "._2nd");
-        Assert.assertEquals(enumVar.baseType, "String");
-        Assert.assertTrue(enumVar.isEnum);
-    }
-
-    @Test(description = "convert a java model with an integer enum and a default value")
-    public void convertIntegerDefaultValueTest() {
-        final IntegerSchema enumSchema = new IntegerSchema();
-        enumSchema.setEnum(Arrays.asList(1, 2, 3));
-        enumSchema.setDefault(2);
-        final Schema model = new Schema().type("object").addProperties("name", enumSchema);
-
-        final DefaultCodegen codegen = new Swift4Codegen();
-        OpenAPI openAPI = TestUtils.createOpenAPIWithOneSchema("sample", model);
-        codegen.setOpenAPI(openAPI);
-        final CodegenModel cm = codegen.fromModel("sample", model);
-
-        Assert.assertEquals(cm.vars.size(), 1);
-
-        final CodegenProperty enumVar = cm.vars.get(0);
-        Assert.assertEquals(enumVar.baseName, "name");
-        Assert.assertEquals(enumVar.dataType, "Int");
-        Assert.assertEquals(enumVar.datatypeWithEnum, "Name");
-        Assert.assertEquals(enumVar.name, "name");
-        Assert.assertEquals(enumVar.defaultValue, "._2");
-        Assert.assertEquals(enumVar.baseType, "Int");
-        Assert.assertTrue(enumVar.isEnum);
-    }
-
-    @Test(description = "convert a java model with an number enum and a default value")
-    public void convertNumberDefaultValueTest() {
-        final NumberSchema enumSchema = new NumberSchema();
-        enumSchema.setEnum(Arrays.asList(new BigDecimal(10), new BigDecimal(100), new BigDecimal(1000)));
-        enumSchema.setDefault(new BigDecimal((100)));
-        final Schema model = new Schema().type("object").addProperties("name", enumSchema);
-
-        final DefaultCodegen codegen = new Swift4Codegen();
-        OpenAPI openAPI = TestUtils.createOpenAPIWithOneSchema("sample", model);
-        codegen.setOpenAPI(openAPI);
-        final CodegenModel cm = codegen.fromModel("sample", model);
-
-        Assert.assertEquals(cm.vars.size(), 1);
-
-        final CodegenProperty enumVar = cm.vars.get(0);
-        Assert.assertEquals(enumVar.baseName, "name");
-        Assert.assertEquals(enumVar.dataType, "Double");
-        Assert.assertEquals(enumVar.datatypeWithEnum, "Name");
-        Assert.assertEquals(enumVar.name, "name");
-        Assert.assertEquals(enumVar.defaultValue, "._100");
-        Assert.assertEquals(enumVar.baseType, "Double");
-        Assert.assertTrue(enumVar.isEnum);
-    }
-}
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4ModelTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4ModelTest.java
deleted file mode 100644
index f87ad8573836..000000000000
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4ModelTest.java
+++ /dev/null
@@ -1,125 +0,0 @@
-/*
- * Copyright 2018 OpenAPI-Generator Contributors (https://openapi-generator.tech)
- * Copyright 2018 SmartBear Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.openapitools.codegen.swift4;
-
-import io.swagger.v3.oas.models.OpenAPI;
-import io.swagger.v3.oas.models.media.*;
-import io.swagger.v3.parser.util.SchemaTypeUtil;
-import org.openapitools.codegen.CodegenModel;
-import org.openapitools.codegen.CodegenProperty;
-import org.openapitools.codegen.DefaultCodegen;
-import org.openapitools.codegen.TestUtils;
-import org.openapitools.codegen.languages.Swift4Codegen;
-import org.testng.Assert;
-import org.testng.annotations.Test;
-
-@SuppressWarnings("static-method")
-public class Swift4ModelTest {
-
-    @Test(description = "convert a simple java model", enabled = true)
-    public void simpleModelTest() {
-        final Schema schema = new Schema()
-                .description("a sample model")
-                .addProperties("id", new IntegerSchema().format(SchemaTypeUtil.INTEGER64_FORMAT))
-                .addProperties("name", new StringSchema())
-                .addProperties("createdAt", new DateTimeSchema())
-                .addProperties("binary", new BinarySchema())
-                .addProperties("byte", new ByteArraySchema())
-                .addProperties("uuid", new UUIDSchema())
-                .addProperties("dateOfBirth", new DateSchema())
-                .addRequiredItem("id")
-                .addRequiredItem("name")
-                .discriminator(new Discriminator().propertyName("test"));
-        final DefaultCodegen codegen = new Swift4Codegen();
-        OpenAPI openAPI = TestUtils.createOpenAPIWithOneSchema("sample", schema);
-        codegen.setOpenAPI(openAPI);
-        final CodegenModel cm = codegen.fromModel("sample", schema);
-
-        Assert.assertEquals(cm.name, "sample");
-        Assert.assertEquals(cm.classname, "Sample");
-        Assert.assertEquals(cm.description, "a sample model");
-        Assert.assertEquals(cm.vars.size(), 7);
-        Assert.assertEquals(cm.getDiscriminatorName(),"test");
-
-        final CodegenProperty property1 = cm.vars.get(0);
-        Assert.assertEquals(property1.baseName, "id");
-        Assert.assertEquals(property1.dataType, "Int64");
-        Assert.assertEquals(property1.name, "id");
-        Assert.assertNull(property1.defaultValue);
-        Assert.assertEquals(property1.baseType, "Int64");
-        Assert.assertTrue(property1.required);
-        Assert.assertTrue(property1.isPrimitiveType);
-        Assert.assertFalse(property1.isContainer);
-
-        final CodegenProperty property2 = cm.vars.get(1);
-        Assert.assertEquals(property2.baseName, "name");
-        Assert.assertEquals(property2.dataType, "String");
-        Assert.assertEquals(property2.name, "name");
-        Assert.assertNull(property2.defaultValue);
-        Assert.assertEquals(property2.baseType, "String");
-        Assert.assertTrue(property2.required);
-        Assert.assertTrue(property2.isPrimitiveType);
-        Assert.assertFalse(property2.isContainer);
-
-        final CodegenProperty property3 = cm.vars.get(2);
-        Assert.assertEquals(property3.baseName, "createdAt");
-        Assert.assertEquals(property3.dataType, "Date");
-        Assert.assertEquals(property3.name, "createdAt");
-        Assert.assertNull(property3.defaultValue);
-        Assert.assertEquals(property3.baseType, "Date");
-        Assert.assertFalse(property3.required);
-        Assert.assertFalse(property3.isContainer);
-
-        final CodegenProperty property4 = cm.vars.get(3);
-        Assert.assertEquals(property4.baseName, "binary");
-        Assert.assertEquals(property4.dataType, "URL");
-        Assert.assertEquals(property4.name, "binary");
-        Assert.assertNull(property4.defaultValue);
-        Assert.assertEquals(property4.baseType, "URL");
-        Assert.assertFalse(property4.required);
-        Assert.assertFalse(property4.isContainer);
-
-        final CodegenProperty property5 = cm.vars.get(4);
-        Assert.assertEquals(property5.baseName, "byte");
-        Assert.assertEquals(property5.dataType, "Data");
-        Assert.assertEquals(property5.name, "byte");
-        Assert.assertNull(property5.defaultValue);
-        Assert.assertEquals(property5.baseType, "Data");
-        Assert.assertFalse(property5.required);
-        Assert.assertFalse(property5.isContainer);
-
-        final CodegenProperty property6 = cm.vars.get(5);
-        Assert.assertEquals(property6.baseName, "uuid");
-        Assert.assertEquals(property6.dataType, "UUID");
-        Assert.assertEquals(property6.name, "uuid");
-        Assert.assertNull(property6.defaultValue);
-        Assert.assertEquals(property6.baseType, "UUID");
-        Assert.assertFalse(property6.required);
-        Assert.assertFalse(property6.isContainer);
-
-        final CodegenProperty property7 = cm.vars.get(6);
-        Assert.assertEquals(property7.baseName, "dateOfBirth");
-        Assert.assertEquals(property7.dataType, "Date");
-        Assert.assertEquals(property7.name, "dateOfBirth");
-        Assert.assertNull(property7.defaultValue);
-        Assert.assertEquals(property7.baseType, "Date");
-        Assert.assertFalse(property7.required);
-        Assert.assertFalse(property7.isContainer);
-    }
-
-}
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4OptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4OptionsTest.java
deleted file mode 100644
index dc4aa7d0943f..000000000000
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift4/Swift4OptionsTest.java
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * Copyright 2018 OpenAPI-Generator Contributors (https://openapi-generator.tech)
- * Copyright 2018 SmartBear Software
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.openapitools.codegen.swift4;
-
-import org.openapitools.codegen.AbstractOptionsTest;
-import org.openapitools.codegen.CodegenConfig;
-import org.openapitools.codegen.languages.Swift4Codegen;
-import org.openapitools.codegen.options.Swift4OptionsProvider;
-
-import static org.mockito.Mockito.mock;
-import static org.mockito.Mockito.verify;
-
-public class Swift4OptionsTest extends AbstractOptionsTest {
-    private Swift4Codegen clientCodegen = mock(Swift4Codegen.class, mockSettings);
-
-    public Swift4OptionsTest() {
-        super(new Swift4OptionsProvider());
-    }
-
-    @Override
-    protected CodegenConfig getCodegenConfig() {
-        return clientCodegen;
-    }
-
-    @SuppressWarnings("unused")
-    @Override
-    protected void verifyOptions() {
-        verify(clientCodegen).setSortParamsByRequiredFlag(Boolean.valueOf(Swift4OptionsProvider.SORT_PARAMS_VALUE));
-        verify(clientCodegen).setProjectName(Swift4OptionsProvider.PROJECT_NAME_VALUE);
-        verify(clientCodegen).setResponseAs(Swift4OptionsProvider.RESPONSE_AS_VALUE.split(","));
-        verify(clientCodegen).setNonPublicApi(Boolean.parseBoolean(Swift4OptionsProvider.NON_PUBLIC_API_REQUIRED_VALUE));
-        verify(clientCodegen).setUnwrapRequired(Boolean.parseBoolean(Swift4OptionsProvider.UNWRAP_REQUIRED_VALUE));
-        verify(clientCodegen).setObjcCompatible(Boolean.parseBoolean(Swift4OptionsProvider.OBJC_COMPATIBLE_VALUE));
-        verify(clientCodegen).setLenientTypeCast(Boolean.parseBoolean(Swift4OptionsProvider.LENIENT_TYPE_CAST_VALUE));
-        verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(Swift4OptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
-    }
-}
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5OptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5OptionsTest.java
index 0550f03de295..20f6c3f46a66 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5OptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5OptionsTest.java
@@ -49,8 +49,8 @@ protected void verifyOptions() {
         verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(Swift5OptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
         verify(clientCodegen).setReadonlyProperties(Boolean.parseBoolean(Swift5OptionsProvider.READONLY_PROPERTIES_VALUE));
         verify(clientCodegen).setRemoveMigrationProjectNameClass(Boolean.parseBoolean(Swift5OptionsProvider.REMOVE_MIGRATION_PROJECT_NAME_CLASS_VALUE));
-        verify(clientCodegen).setGenerateFrozenEnums(Boolean.parseBoolean(Swift5OptionsProvider.GENERATE_FROZEN_ENUMS_VALUE));
         verify(clientCodegen).setGenerateModelAdditionalProperties(Boolean.parseBoolean(Swift5OptionsProvider.GENERATE_MODEL_ADDITIONAL_PROPERTIES_VALUE));
         verify(clientCodegen).setHashableModels(Boolean.parseBoolean(Swift5OptionsProvider.HASHABLE_MODELS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(Swift5OptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/aurelia/TypeScriptAureliaClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/aurelia/TypeScriptAureliaClientOptionsTest.java
index cd247de1190c..be1801e6401b 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/aurelia/TypeScriptAureliaClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/aurelia/TypeScriptAureliaClientOptionsTest.java
@@ -45,5 +45,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setParamNaming(TypeScriptAureliaClientOptionsProvider.PARAM_NAMING_VALUE);
         verify(clientCodegen).setSupportsES6(TypeScriptAureliaClientOptionsProvider.SUPPORTS_ES6_VALUE);
         verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(TypeScriptAureliaClientOptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(TypeScriptAureliaClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/fetch/TypeScriptFetchClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/fetch/TypeScriptFetchClientOptionsTest.java
index 7b29653b31a4..afd91bd47253 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/fetch/TypeScriptFetchClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/fetch/TypeScriptFetchClientOptionsTest.java
@@ -48,5 +48,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setTypescriptThreePlus(Boolean.valueOf(TypeScriptFetchClientOptionsProvider.TYPESCRIPT_THREE_PLUS));
         verify(clientCodegen).setWithoutRuntimeChecks(Boolean.valueOf(TypeScriptFetchClientOptionsProvider.WITHOUT_RUNTIME_CHECKS));
         verify(clientCodegen).setSagasAndRecords(Boolean.valueOf(TypeScriptFetchClientOptionsProvider.SAGAS_AND_RECORDS));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(TypeScriptFetchClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangular/TypeScriptAngularClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangular/TypeScriptAngularClientOptionsTest.java
index 5359b81e6a52..38b1f0ee4d01 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangular/TypeScriptAngularClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangular/TypeScriptAngularClientOptionsTest.java
@@ -47,5 +47,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(TypeScriptAngularClientOptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
         verify(clientCodegen).setQueryParamObjectFormat(TypeScriptAngularClientOptionsProvider.QUERY_PARAM_OBJECT_FORMAT_VALUE);
         verify(clientCodegen).setParamNaming(TypeScriptAngularClientOptionsProvider.PARAM_NAMING_VALUE);
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(TypeScriptAngularClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangularjs/TypeScriptAngularJsClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangularjs/TypeScriptAngularJsClientOptionsTest.java
index 54710992d911..b2c9c066b819 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangularjs/TypeScriptAngularJsClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptangularjs/TypeScriptAngularJsClientOptionsTest.java
@@ -45,5 +45,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setParamNaming(TypeScriptAngularJsClientOptionsProvider.PARAM_NAMING_VALUE);
         verify(clientCodegen).setSupportsES6(Boolean.valueOf(TypeScriptAngularJsClientOptionsProvider.SUPPORTS_ES6_VALUE));
         verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(TypeScriptAngularJsClientOptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(TypeScriptAngularJsClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptnestjs/TypeScriptNestjsClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptnestjs/TypeScriptNestjsClientOptionsTest.java
index 5f2138a66c29..ba042c8471f2 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptnestjs/TypeScriptNestjsClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptnestjs/TypeScriptNestjsClientOptionsTest.java
@@ -46,5 +46,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setSupportsES6(Boolean.valueOf(TypeScriptNestjsClientOptionsProvider.SUPPORTS_ES6_VALUE));
         verify(clientCodegen).setStringEnums(Boolean.parseBoolean(TypeScriptNestjsClientOptionsProvider.STRING_ENUMS_VALUE));
         verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(TypeScriptNestjsClientOptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(TypeScriptNestjsClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptnode/TypeScriptNodeClientOptionsTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptnode/TypeScriptNodeClientOptionsTest.java
index 414c63dd279a..680759c870c9 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptnode/TypeScriptNodeClientOptionsTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/typescript/typescriptnode/TypeScriptNodeClientOptionsTest.java
@@ -45,5 +45,6 @@ protected void verifyOptions() {
         verify(clientCodegen).setParamNaming(TypeScriptNodeClientOptionsProvider.PARAM_NAMING_VALUE);
         verify(clientCodegen).setSupportsES6(Boolean.valueOf(TypeScriptNodeClientOptionsProvider.SUPPORTS_ES6_VALUE));
         verify(clientCodegen).setPrependFormOrBodyParameters(Boolean.valueOf(TypeScriptNodeClientOptionsProvider.PREPEND_FORM_OR_BODY_PARAMETERS_VALUE));
+        verify(clientCodegen).setEnumUnknownDefaultCase(Boolean.parseBoolean(TypeScriptNodeClientOptionsProvider.ENUM_UNKNOWN_DEFAULT_CASE_VALUE));
     }
 }
diff --git a/samples/client/petstore/kotlin-enum-default-value/.openapi-generator/FILES b/samples/client/petstore/kotlin-enum-default-value/.openapi-generator/FILES
index 66329670bf9d..edff1ccea7b5 100644
--- a/samples/client/petstore/kotlin-enum-default-value/.openapi-generator/FILES
+++ b/samples/client/petstore/kotlin-enum-default-value/.openapi-generator/FILES
@@ -22,6 +22,7 @@ src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
 src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
 src/main/kotlin/org/openapitools/client/infrastructure/ResponseExtensions.kt
 src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+src/main/kotlin/org/openapitools/client/infrastructure/SerializerHelper.kt
 src/main/kotlin/org/openapitools/client/infrastructure/URIAdapter.kt
 src/main/kotlin/org/openapitools/client/infrastructure/UUIDAdapter.kt
 src/main/kotlin/org/openapitools/client/models/ModelWithEnumPropertyHavingDefault.kt
diff --git a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
index ef0c18333845..3925a4181e8a 100644
--- a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
+++ b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/apis/DefaultApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.ModelWithEnumPropertyHavingDefault
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
index e22592e47d74..755f8240ed47 100644
--- a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+++ b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -1,6 +1,7 @@
 package org.openapitools.client.infrastructure
 
 import com.squareup.moshi.Moshi
+import com.squareup.moshi.adapters.EnumJsonAdapter
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
 
 object Serializer {
@@ -18,6 +19,7 @@ object Serializer {
 
     @JvmStatic
     val moshi: Moshi by lazy {
+        SerializerHelper.addEnumUnknownDefaultCase(moshiBuilder)
         moshiBuilder.build()
     }
 }
diff --git a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/SerializerHelper.kt b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/SerializerHelper.kt
new file mode 100644
index 000000000000..d3789e4823bd
--- /dev/null
+++ b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/infrastructure/SerializerHelper.kt
@@ -0,0 +1,12 @@
+package org.openapitools.client.infrastructure
+
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.adapters.EnumJsonAdapter
+
+object SerializerHelper {
+    fun addEnumUnknownDefaultCase(moshiBuilder: Moshi.Builder): Moshi.Builder {
+        return moshiBuilder
+            .add(org.openapitools.client.models.ModelWithEnumPropertyHavingDefault.PropertyName::class.java, EnumJsonAdapter.create(org.openapitools.client.models.ModelWithEnumPropertyHavingDefault.PropertyName::class.java)
+                .withUnknownFallback(org.openapitools.client.models.ModelWithEnumPropertyHavingDefault.PropertyName.unknownDefaultOpenApi))
+    }
+}
diff --git a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/models/ModelWithEnumPropertyHavingDefault.kt b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/models/ModelWithEnumPropertyHavingDefault.kt
index 80f0176dc0ca..16982beb8891 100644
--- a/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/models/ModelWithEnumPropertyHavingDefault.kt
+++ b/samples/client/petstore/kotlin-enum-default-value/src/main/kotlin/org/openapitools/client/models/ModelWithEnumPropertyHavingDefault.kt
@@ -43,10 +43,11 @@ data class ModelWithEnumPropertyHavingDefault (
     /**
      * 
      *
-     * Values: vALUE
+     * Values: vALUE,unknownDefaultOpenApi
      */
     enum class PropertyName(val value: kotlin.String) {
-        @Json(name = "VALUE") vALUE("VALUE");
+        @Json(name = "VALUE") vALUE("VALUE"),
+        @Json(name = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index b774e10e7b81..54b52a811860 100644
--- a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.google.gson.annotations.SerializedName
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @SerializedName(value = "available") available("available"),
+         @SerializedName(value = "pending") pending("pending"),
+         @SerializedName(value = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d9cc68f0042f..5dff82cca137 100644
--- a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.google.gson.annotations.SerializedName
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index efbff7928151..3cd3a17289b9 100644
--- a/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-gson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.google.gson.annotations.SerializedName
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index b774e10e7b81..b07f6fb114f3 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.fasterxml.jackson.annotation.JsonProperty
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @JsonProperty(value = "available") AVAILABLE("available"),
+         @JsonProperty(value = "pending") PENDING("pending"),
+         @JsonProperty(value = "sold") SOLD("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d9cc68f0042f..5f5f7ecffe81 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.fasterxml.jackson.annotation.JsonProperty
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index efbff7928151..332503b18953 100644
--- a/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-jackson/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.fasterxml.jackson.annotation.JsonProperty
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index dcb8d97586b5..5c62ed5b98f7 100644
--- a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -247,7 +249,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
@@ -320,7 +322,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun getAllPetsRequestConfig(lastUpdated: java.time.OffsetDateTime?) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 if (lastUpdated != null) {
                     put("lastUpdated", listOf(parseDateToQueryString(lastUpdated)))
diff --git a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d9cc68f0042f..916a865f7acc 100644
--- a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index efbff7928151..1c294b5e2215 100644
--- a/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-json-request-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 1cd9901c0f91..6b26a13e51ae 100644
--- a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.google.gson.annotations.SerializedName
+
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import org.openapitools.client.infrastructure.ApiClient
@@ -187,6 +189,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @SerializedName(value = "available") available("available"),
+         @SerializedName(value = "pending") pending("pending"),
+         @SerializedName(value = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -200,7 +212,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    suspend fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> = withContext(Dispatchers.IO) {
+    suspend fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> = withContext(Dispatchers.IO) {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return@withContext when (localVarResponse.responseType) {
@@ -228,7 +240,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    suspend fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> = withContext(Dispatchers.IO) {
+    suspend fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> = withContext(Dispatchers.IO) {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return@withContext request<Unit, kotlin.collections.List<Pet>>(
@@ -242,9 +254,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -322,7 +334,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 430d9449c484..ffa098db6ca1 100644
--- a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.google.gson.annotations.SerializedName
+
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import org.openapitools.client.infrastructure.ApiClient
diff --git a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index d318fa7477df..724e2d6fd2e8 100644
--- a/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-jvm-okhttp4-coroutines/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.google.gson.annotations.SerializedName
+
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.withContext
 import org.openapitools.client.infrastructure.ApiClient
@@ -445,7 +447,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index b774e10e7b81..601ca6b01f88 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @Json(name = "available") available("available"),
+         @Json(name = "pending") pending("pending"),
+         @Json(name = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d9cc68f0042f..916a865f7acc 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index efbff7928151..1c294b5e2215 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 33d1e110f122..4eefd44019f8 100644
--- a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(bas
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     internal enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @Json(name = "available") available("available"),
+         @Json(name = "pending") pending("pending"),
+         @Json(name = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(bas
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(bas
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(bas
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ internal class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(bas
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index 02201f04d42b..e5d64330d94d 100644
--- a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 3475e9c4695e..363f3924a001 100644
--- a/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-nonpublic/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ internal class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(ba
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 8f8335f8b75b..9e40a8d6be31 100644
--- a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @Json(name = "available") available("available"),
+         @Json(name = "pending") pending("pending"),
+         @Json(name = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet>? {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet>? {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index b35fda447217..a305a6661a0c 100644
--- a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index 87ad7db8960f..bc8b00bc288a 100644
--- a/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-nullable/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-okhttp3/.openapi-generator/FILES b/samples/client/petstore/kotlin-okhttp3/.openapi-generator/FILES
index c7a409ac169e..2710ee42441f 100644
--- a/samples/client/petstore/kotlin-okhttp3/.openapi-generator/FILES
+++ b/samples/client/petstore/kotlin-okhttp3/.openapi-generator/FILES
@@ -31,6 +31,7 @@ src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
 src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
 src/main/kotlin/org/openapitools/client/infrastructure/ResponseExtensions.kt
 src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+src/main/kotlin/org/openapitools/client/infrastructure/SerializerHelper.kt
 src/main/kotlin/org/openapitools/client/infrastructure/URIAdapter.kt
 src/main/kotlin/org/openapitools/client/infrastructure/UUIDAdapter.kt
 src/main/kotlin/org/openapitools/client/models/Category.kt
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index b774e10e7b81..601ca6b01f88 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @Json(name = "available") available("available"),
+         @Json(name = "pending") pending("pending"),
+         @Json(name = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d9cc68f0042f..916a865f7acc 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index efbff7928151..1c294b5e2215 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
index e22592e47d74..755f8240ed47 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -1,6 +1,7 @@
 package org.openapitools.client.infrastructure
 
 import com.squareup.moshi.Moshi
+import com.squareup.moshi.adapters.EnumJsonAdapter
 import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
 
 object Serializer {
@@ -18,6 +19,7 @@ object Serializer {
 
     @JvmStatic
     val moshi: Moshi by lazy {
+        SerializerHelper.addEnumUnknownDefaultCase(moshiBuilder)
         moshiBuilder.build()
     }
 }
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/SerializerHelper.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/SerializerHelper.kt
new file mode 100644
index 000000000000..e00c195ee2c0
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/SerializerHelper.kt
@@ -0,0 +1,14 @@
+package org.openapitools.client.infrastructure
+
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.adapters.EnumJsonAdapter
+
+object SerializerHelper {
+    fun addEnumUnknownDefaultCase(moshiBuilder: Moshi.Builder): Moshi.Builder {
+        return moshiBuilder
+            .add(org.openapitools.client.models.Order.Status::class.java, EnumJsonAdapter.create(org.openapitools.client.models.Order.Status::class.java)
+                .withUnknownFallback(org.openapitools.client.models.Order.Status.unknownDefaultOpenApi))
+            .add(org.openapitools.client.models.Pet.Status::class.java, EnumJsonAdapter.create(org.openapitools.client.models.Pet.Status::class.java)
+                .withUnknownFallback(org.openapitools.client.models.Pet.Status.unknownDefaultOpenApi))
+    }
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Order.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Order.kt
index 1c87feb6972d..7195f3366927 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Order.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Order.kt
@@ -60,12 +60,13 @@ data class Order (
     /**
      * Order Status
      *
-     * Values: placed,approved,delivered
+     * Values: placed,approved,delivered,unknownDefaultOpenApi
      */
     enum class Status(val value: kotlin.String) {
         @Json(name = "placed") placed("placed"),
         @Json(name = "approved") approved("approved"),
-        @Json(name = "delivered") delivered("delivered");
+        @Json(name = "delivered") delivered("delivered"),
+        @Json(name = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Pet.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Pet.kt
index fb28ee922256..801bd2a82221 100644
--- a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Pet.kt
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Pet.kt
@@ -62,12 +62,13 @@ data class Pet (
     /**
      * pet status in the store
      *
-     * Values: available,pending,sold
+     * Values: available,pending,sold,unknownDefaultOpenApi
      */
     enum class Status(val value: kotlin.String) {
         @Json(name = "available") available("available"),
         @Json(name = "pending") pending("pending"),
-        @Json(name = "sold") sold("sold");
+        @Json(name = "sold") sold("sold"),
+        @Json(name = "unknown_default_open_api") unknownDefaultOpenApi("unknown_default_open_api");
     }
 }
 
diff --git a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index 40c875dcdc7e..870811a2c93a 100644
--- a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @Json(name = "available") available("available"),
+         @Json(name = "pending") pending("pending"),
+         @Json(name = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d9cc68f0042f..916a865f7acc 100644
--- a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index efbff7928151..1c294b5e2215 100644
--- a/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-string/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index b774e10e7b81..601ca6b01f88 100644
--- a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @Json(name = "available") available("available"),
+         @Json(name = "pending") pending("pending"),
+         @Json(name = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d9cc68f0042f..916a865f7acc 100644
--- a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index efbff7928151..1c294b5e2215 100644
--- a/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-threetenbp/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/apis/EnumApi.kt b/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/apis/EnumApi.kt
index 9e39ffb9d00d..325c66305b88 100644
--- a/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/apis/EnumApi.kt
+++ b/samples/client/petstore/kotlin-uppercase-enum/src/main/kotlin/org/openapitools/client/apis/EnumApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.PetEnum
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index b774e10e7b81..601ca6b01f88 100644
--- a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -25,6 +25,8 @@ import java.io.IOException
 import org.openapitools.client.models.ModelApiResponse
 import org.openapitools.client.models.Pet
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -185,6 +187,16 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
         )
     }
 
+    /**
+     * enum for parameter status
+     */
+     enum class Status_findPetsByStatus(val value: kotlin.String) {
+         @Json(name = "available") available("available"),
+         @Json(name = "pending") pending("pending"),
+         @Json(name = "sold") sold("sold"),
+         ;
+     }
+
     /**
     * Finds Pets by status
     * Multiple status values can be provided with comma separated strings
@@ -198,7 +210,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class, UnsupportedOperationException::class, ClientException::class, ServerException::class)
-    fun findPetsByStatus(status: kotlin.collections.List<kotlin.String>) : kotlin.collections.List<Pet> {
+    fun findPetsByStatus(status: kotlin.collections.List<Status_findPetsByStatus>) : kotlin.collections.List<Pet> {
         val localVarResponse = findPetsByStatusWithHttpInfo(status = status)
 
         return when (localVarResponse.responseType) {
@@ -226,7 +238,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     @Suppress("UNCHECKED_CAST")
     @Throws(IllegalStateException::class, IOException::class)
-    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<kotlin.String>) : ApiResponse<kotlin.collections.List<Pet>?> {
+    fun findPetsByStatusWithHttpInfo(status: kotlin.collections.List<Status_findPetsByStatus>) : ApiResponse<kotlin.collections.List<Pet>?> {
         val localVariableConfig = findPetsByStatusRequestConfig(status = status)
 
         return request<Unit, kotlin.collections.List<Pet>>(
@@ -240,9 +252,9 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     * @param status Status values that need to be considered for filter 
     * @return RequestConfig
     */
-    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
+    fun findPetsByStatusRequestConfig(status: kotlin.collections.List<Status_findPetsByStatus>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("status", toMultiValue(status.toList(), "csv"))
             }
@@ -320,7 +332,7 @@ class PetApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     @Deprecated(message = "This operation is deprecated.")
     fun findPetsByTagsRequestConfig(tags: kotlin.collections.List<kotlin.String>) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("tags", toMultiValue(tags.toList(), "csv"))
             }
diff --git a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index d9cc68f0042f..916a865f7acc 100644
--- a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.Order
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
diff --git a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index efbff7928151..1c294b5e2215 100644
--- a/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -24,6 +24,8 @@ import java.io.IOException
 
 import org.openapitools.client.models.User
 
+import com.squareup.moshi.Json
+
 import org.openapitools.client.infrastructure.ApiClient
 import org.openapitools.client.infrastructure.ApiResponse
 import org.openapitools.client.infrastructure.ClientException
@@ -443,7 +445,7 @@ class UserApi(basePath: kotlin.String = defaultBasePath) : ApiClient(basePath) {
     */
     fun loginUserRequestConfig(username: kotlin.String, password: kotlin.String) : RequestConfig<Unit> {
         val localVariableBody = null
-        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, List<kotlin.String>>()
+        val localVariableQuery: MultiValueMap = mutableMapOf<kotlin.String, kotlin.collections.List<kotlin.String>>()
             .apply {
                 put("username", listOf(username.toString()))
                 put("password", listOf(password.toString()))
diff --git a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumArrays.swift b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumArrays.swift
index 321066b9f4ed..e41babad70f4 100644
--- a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumArrays.swift
+++ b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumArrays.swift
@@ -15,20 +15,12 @@ public struct EnumArrays: Codable, Hashable {
     public enum JustSymbol: String, Codable, CaseIterable, CaseIterableDefaultsLast {
         case greaterThanOrEqualTo = ">="
         case dollar = "$"
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
+        case unknownDefaultOpenApi = "unknown_default_open_api"
     }
     public enum ArrayEnum: String, Codable, CaseIterable, CaseIterableDefaultsLast {
         case fish = "fish"
         case crab = "crab"
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
+        case unknownDefaultOpenApi = "unknown_default_open_api"
     }
     public var justSymbol: JustSymbol?
     public var arrayEnum: [ArrayEnum]?
diff --git a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumClass.swift b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumClass.swift
index eef3045b2915..232f04f3ddd3 100644
--- a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumClass.swift
+++ b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumClass.swift
@@ -14,9 +14,5 @@ public enum EnumClass: String, Codable, CaseIterable, CaseIterableDefaultsLast {
     case abc = "_abc"
     case efg = "-efg"
     case xyz = "(xyz)"
-    // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-    // If new enum cases are added that are unknown to the spec/client, they are safely
-    // decoded to this case. The raw value of this case is a dummy value that attempts
-    // to avoids collisions with previously specified cases.
-    case unknownDefaultOpenAPI = "unknown_default_open_api"
+    case unknownDefaultOpenApi = "unknown_default_open_api"
 }
diff --git a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumTest.swift b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumTest.swift
index d6a96c72d97e..72eaac6069a6 100644
--- a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumTest.swift
+++ b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/EnumTest.swift
@@ -16,49 +16,23 @@ public struct EnumTest: Codable, Hashable {
         case upper = "UPPER"
         case lower = "lower"
         case empty = ""
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
+        case unknownDefaultOpenApi = "unknown_default_open_api"
     }
     public enum EnumStringRequired: String, Codable, CaseIterable, CaseIterableDefaultsLast {
         case upper = "UPPER"
         case lower = "lower"
         case empty = ""
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
+        case unknownDefaultOpenApi = "unknown_default_open_api"
     }
     public enum EnumInteger: Int, Codable, CaseIterable, CaseIterableDefaultsLast {
         case _1 = 1
         case number1 = -1
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        //
-        // 192, used to calculate the raw value, was the Swift Evolution proposal for
-        // frozen/non-frozen enums.
-        // [SE-0192](https://github.com/apple/swift-evolution/blob/master/proposals/0192-non-exhaustive-enums.md)
-        //
-        case unknownDefaultOpenAPI = -11184809 // Int.min / 192
+        case unknownDefaultOpenApi = 11184809
     }
     public enum EnumNumber: Double, Codable, CaseIterable, CaseIterableDefaultsLast {
         case _11 = 1.1
         case number12 = -1.2
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        //
-        // 192, used to calculate the raw value, was the Swift Evolution proposal for
-        // frozen/non-frozen enums.
-        // [SE-0192](https://github.com/apple/swift-evolution/blob/master/proposals/0192-non-exhaustive-enums.md)
-        //
-        case unknownDefaultOpenAPI = -11184809 // Int.min / 192
+        case unknownDefaultOpenApi = 11184809
     }
     public var enumString: EnumString?
     public var enumStringRequired: EnumStringRequired
diff --git a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/MapTest.swift b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/MapTest.swift
index c0b5a369451d..fcae4e7e9372 100644
--- a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/MapTest.swift
+++ b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/MapTest.swift
@@ -15,11 +15,7 @@ public struct MapTest: Codable, Hashable {
     public enum MapOfEnumString: String, Codable, CaseIterable, CaseIterableDefaultsLast {
         case upper = "UPPER"
         case lower = "lower"
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
+        case unknownDefaultOpenApi = "unknown_default_open_api"
     }
     public var mapMapOfString: [String: [String: String]]?
     public var mapOfEnumString: [String: String]?
diff --git a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/Order.swift b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/Order.swift
index 5615d10ff4c5..57c1c4f866e5 100644
--- a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/Order.swift
+++ b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/Order.swift
@@ -16,11 +16,7 @@ public struct Order: Codable, Hashable {
         case placed = "placed"
         case approved = "approved"
         case delivered = "delivered"
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
+        case unknownDefaultOpenApi = "unknown_default_open_api"
     }
     public var id: Int64?
     public var petId: Int64?
diff --git a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/OuterEnum.swift b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/OuterEnum.swift
index e418b2c445bb..4c1af47007e5 100644
--- a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/OuterEnum.swift
+++ b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/OuterEnum.swift
@@ -14,9 +14,5 @@ public enum OuterEnum: String, Codable, CaseIterable, CaseIterableDefaultsLast {
     case placed = "placed"
     case approved = "approved"
     case delivered = "delivered"
-    // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-    // If new enum cases are added that are unknown to the spec/client, they are safely
-    // decoded to this case. The raw value of this case is a dummy value that attempts
-    // to avoids collisions with previously specified cases.
-    case unknownDefaultOpenAPI = "unknown_default_open_api"
+    case unknownDefaultOpenApi = "unknown_default_open_api"
 }
diff --git a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/Pet.swift b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/Pet.swift
index 81afbc4b2a16..45b4cff8e1e5 100644
--- a/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/Pet.swift
+++ b/samples/client/petstore/swift5/frozenEnums/PetstoreClient/Classes/OpenAPIs/Models/Pet.swift
@@ -16,11 +16,7 @@ public struct Pet: Codable, Hashable {
         case available = "available"
         case pending = "pending"
         case sold = "sold"
-        // This case is a catch-all generated by OpenAPI such that the enum is "non-frozen".
-        // If new enum cases are added that are unknown to the spec/client, they are safely
-        // decoded to this case. The raw value of this case is a dummy value that attempts
-        // to avoids collisions with previously specified cases.
-        case unknownDefaultOpenAPI = "unknown_default_open_api"
+        case unknownDefaultOpenApi = "unknown_default_open_api"
     }
     public var id: Int64?
     public var category: Category?