diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GoClientExperimentalCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GoClientExperimentalCodegen.java
index e541998cddc2..76d265049693 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GoClientExperimentalCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GoClientExperimentalCodegen.java
@@ -36,14 +36,12 @@ public GoClientExperimentalCodegen() {
         outputFolder = "generated-code/go-experimental";
         embeddedTemplateDir = templateDir = "go-experimental";
 
-        generatorMetadata = GeneratorMetadata.newBuilder(generatorMetadata)
-                .stability(Stability.EXPERIMENTAL)
-                .build();
+        generatorMetadata = GeneratorMetadata.newBuilder(generatorMetadata).stability(Stability.EXPERIMENTAL).build();
     }
 
     /**
-     * Configures a friendly name for the generator.  This will be used by the generator
-     * to select the library with the -g flag.
+     * Configures a friendly name for the generator. This will be used by the
+     * generator to select the library with the -g flag.
      *
      * @return the friendly name for the generator
      */
@@ -53,7 +51,7 @@ public String getName() {
     }
 
     /**
-     * Returns human-friendly help for the generator.  Provide the consumer with help
+     * Returns human-friendly help for the generator. Provide the consumer with help
      * tips, parameters here
      *
      * @return A string value for the help message
@@ -70,24 +68,25 @@ public void processOpts() {
     }
 
     @Override
-     public Map<String, Object> postProcessModels(Map<String, Object> objs) {
+    public Map<String, Object> postProcessModels(Map<String, Object> objs) {
         objs = super.postProcessModels(objs);
-        List<Map<String, String>> imports = (List<Map<String, String>>) objs.get("imports");
 
-        boolean addedErrorsImport = false;
         List<Map<String, Object>> models = (List<Map<String, Object>>) objs.get("models");
         for (Map<String, Object> m : models) {
             Object v = m.get("model");
             if (v instanceof CodegenModel) {
                 CodegenModel model = (CodegenModel) v;
-                if (!model.isEnum) {
-                    imports.add(createMapping("import", "encoding/json"));
+                if (model.isEnum) {
+                    continue;
                 }
+
                 for (CodegenProperty param : model.vars) {
-                    if (!addedErrorsImport && param.required) {
-                        imports.add(createMapping("import", "errors"));
-                        addedErrorsImport = true;
+                    if (!param.isNullable) {
+                        continue;
                     }
+
+                    param.dataType = "Nullable" + Character.toUpperCase(param.dataType.charAt(0))
+                            + param.dataType.substring(1);
                 }
             }
         }
diff --git a/modules/openapi-generator/src/main/resources/go-experimental/model.mustache b/modules/openapi-generator/src/main/resources/go-experimental/model.mustache
index 2b97b31b3cfa..f1f3dd8c1250 100644
--- a/modules/openapi-generator/src/main/resources/go-experimental/model.mustache
+++ b/modules/openapi-generator/src/main/resources/go-experimental/model.mustache
@@ -1,15 +1,15 @@
 {{>partial_header}}
 package {{packageName}}
+
 {{#models}}
-{{#imports}}
-{{#-first}}
 import (
-{{/-first}}
+	"bytes"
+	"encoding/json"
+{{#imports}}
 	"{{import}}"
-{{#-last}}
-)
-{{/-last}}
 {{/imports}}
+)
+
 {{#model}}
 {{#isEnum}}
 // {{{classname}}} {{#description}}{{{.}}}{{/description}}{{^description}}the model '{{{classname}}}'{{/description}}
@@ -25,6 +25,32 @@ const (
 	{{/enumVars}}
 	{{/allowableValues}}
 )
+
+type Nullable{{{classname}}} struct {
+	Value {{{classname}}}
+	ExplicitNull bool
+}
+
+func (v Nullable{{{classname}}}) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != "":
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
+
+func (v *Nullable{{{classname}}}) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
+
 {{/isEnum}}
 {{^isEnum}}
 // {{classname}}{{#description}} {{{description}}}{{/description}}{{^description}} struct for {{{classname}}}{{/description}}
@@ -35,15 +61,32 @@ type {{classname}} struct {
 {{#description}}
 	// {{{description}}}
 {{/description}}
-	{{name}} *{{{dataType}}} `json:"{{baseName}},omitempty"{{#withXml}} xml:"{{baseName}}{{#isXmlAttribute}},attr{{/isXmlAttribute}}"{{/withXml}}{{#vendorExtensions.x-go-custom-tag}} {{{.}}}{{/vendorExtensions.x-go-custom-tag}}`
-{{#isNullable}}	isExplicitNull{{name}} bool `json:"-"{{#withXml}} xml:"-"{{/withXml}}`{{/isNullable}}
+	{{name}} {{^required}}*{{/required}}{{{dataType}}} `json:"{{baseName}}{{^required}},omitempty{{/required}}"{{#withXml}} xml:"{{baseName}}{{#isXmlAttribute}},attr{{/isXmlAttribute}}"{{/withXml}}{{#vendorExtensions.x-go-custom-tag}} {{{.}}}{{/vendorExtensions.x-go-custom-tag}}`
 {{/vars}}
 }
 {{/isEnum}}
 
 {{^isEnum}}
 {{#vars}}
-// Get{{name}} returns the {{name}} field if non-nil, zero value otherwise.
+{{#required}}
+// Get{{name}} returns the {{name}} field value
+func (o *{{classname}}) Get{{name}}() {{dataType}} {
+	if o == nil {
+		var ret {{dataType}}
+		return ret
+	}
+
+	return o.{{name}}
+}
+
+// Set{{name}} sets field value
+func (o *{{classname}}) Set{{name}}(v {{dataType}}) {
+	o.{{name}} = v
+}
+
+{{/required}}
+{{^required}}
+// Get{{name}} returns the {{name}} field value if set, zero value otherwise.
 func (o *{{classname}}) Get{{name}}() {{dataType}} {
 	if o == nil || o.{{name}} == nil {
 		var ret {{dataType}}
@@ -52,7 +95,7 @@ func (o *{{classname}}) Get{{name}}() {{dataType}} {
 	return *o.{{name}}
 }
 
-// Get{{name}}Ok returns a tuple with the {{name}} field if it's non-nil, zero value otherwise
+// Get{{name}}Ok returns a tuple with the {{name}} field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *{{classname}}) Get{{name}}Ok() ({{dataType}}, bool) {
 	if o == nil || o.{{name}} == nil {
@@ -76,54 +119,30 @@ func (o *{{classname}}) Set{{name}}(v {{dataType}}) {
 	o.{{name}} = &v
 }
 
-{{#isNullable}}
-// Set{{name}}ExplicitNull (un)sets {{name}} to be considered as explicit "null" value
-// when serializing to JSON (pass true as argument to set this, false to unset)
-// The {{name}} value is set to nil even if false is passed
-func (o *{{classname}}) Set{{name}}ExplicitNull(b bool) {
-	o.{{name}} = nil
-	o.isExplicitNull{{name}} = b
-}
-{{/isNullable}}
+{{/required}}
 {{/vars}}
+type Nullable{{{classname}}} struct {
+	Value {{{classname}}}
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o {{classname}}) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	{{#vars}}
-	{{#required}}
-	{{! if argument is required and not nullable, it can't be nil}}
-	{{^isNullable}}
-	if o.{{name}} == nil {
-		return nil, errors.New("{{name}} is required and not nullable, but was not set on {{classname}}")
-	}{{/isNullable}}
-	{{! if argument is required and nullable, it *must* have isExplicitNull<name> set to true when it's nil}}
-	{{#isNullable}}
-	if o.{{name}} == nil && !o.isExplicitNull{{name}} {
-		return nil, errors.New("{{name}} is required and nullable, but it wasn't set to be explicit null")
-	}
-	{{/isNullable}}
-	{{/required}}
-	{{! if argument is nullable, only serialize it if it is nil *and* was explicitly set to nil}}
-	{{#isNullable}}
-	if o.{{name}} == nil {
-		if o.isExplicitNull{{name}} {
-			toSerialize["{{baseName}}"] = o.{{name}}
-		}
-	} else {
-		toSerialize["{{baseName}}"] = o.{{name}}
-	}
-	{{/isNullable}}
-	{{! if argument is not nullable, don't set it if it is nil}}
-	{{^isNullable}}
-	if o.{{name}} != nil {
-		toSerialize["{{baseName}}"] = o.{{name}}
-	}
-	{{/isNullable}}
-	{{/vars}}
-	return json.Marshal(toSerialize)
+func (v Nullable{{{classname}}}) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *Nullable{{{classname}}}) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 {{/isEnum}}
 
 {{/model}}
diff --git a/modules/openapi-generator/src/main/resources/go-experimental/utils.mustache b/modules/openapi-generator/src/main/resources/go-experimental/utils.mustache
index e3598373cb4a..4502401b6ea4 100644
--- a/modules/openapi-generator/src/main/resources/go-experimental/utils.mustache
+++ b/modules/openapi-generator/src/main/resources/go-experimental/utils.mustache
@@ -1,7 +1,14 @@
 {{>partial_header}}
 package {{packageName}}
 
-import "time"
+import (
+    "bytes"
+    "encoding/json"
+    "errors"
+    "time"
+)
+
+var ErrInvalidNullable = errors.New("nullable cannot have non-zero Value and ExplicitNull simultaneously")
 
 // PtrBool is a helper routine that returns a pointer to given integer value.
 func PtrBool(v bool) *bool { return &v }
@@ -15,9 +22,6 @@ func PtrInt32(v int32) *int32 { return &v }
 // PtrInt64 is a helper routine that returns a pointer to given integer value.
 func PtrInt64(v int64) *int64 { return &v }
 
-// PtrFloat is a helper routine that returns a pointer to given float value.
-func PtrFloat(v float32) *float32 { return &v }
-
 // PtrFloat32 is a helper routine that returns a pointer to given float value.
 func PtrFloat32(v float32) *float32 { return &v }
 
@@ -28,4 +32,205 @@ func PtrFloat64(v float64) *float64 { return &v }
 func PtrString(v string) *string { return &v }
 
 // PtrTime is helper routine that returns a pointer to given Time value.
-func PtrTime(v time.Time) *time.Time { return &v }
\ No newline at end of file
+func PtrTime(v time.Time) *time.Time { return &v }
+
+type NullableBool struct {
+    Value bool
+    ExplicitNull bool
+}
+
+func (v NullableBool) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableBool) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableInt struct {
+    Value int
+    ExplicitNull bool
+}
+
+func (v NullableInt) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+
+func (v *NullableInt) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableInt32 struct {
+    Value int32
+    ExplicitNull bool
+}
+
+func (v NullableInt32) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableInt32) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableInt64 struct {
+    Value int64
+    ExplicitNull bool
+}
+
+func (v NullableInt64) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableInt64) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableFloat32 struct {
+    Value float32
+    ExplicitNull bool
+}
+
+func (v NullableFloat32) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0.0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableFloat32) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableFloat64 struct {
+    Value float64
+    ExplicitNull bool
+}
+
+func (v NullableFloat64) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0.0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableFloat64) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableString struct {
+    Value string
+    ExplicitNull bool
+}
+
+func (v NullableString) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != "":
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableString) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableTime struct {
+    Value time.Time
+    ExplicitNull bool
+}
+
+func (v NullableTime) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && !v.Value.IsZero():
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return v.Value.MarshalJSON()
+    }
+}
+
+func (v *NullableTime) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
\ No newline at end of file
diff --git a/samples/client/petstore/go-experimental/auth_test.go b/samples/client/petstore/go-experimental/auth_test.go
index 1bb5d8175635..b788cc1199e3 100644
--- a/samples/client/petstore/go-experimental/auth_test.go
+++ b/samples/client/petstore/go-experimental/auth_test.go
@@ -37,8 +37,8 @@ func TestOAuth2(t *testing.T) {
 	tokenSource := cfg.TokenSource(createContext(nil), &tok)
 	auth := context.WithValue(context.Background(), sw.ContextOAuth2, tokenSource)
 
-	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: sw.PtrString("gopher"),
-		PhotoUrls: &[]string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
+	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: "gopher",
+		PhotoUrls: []string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
 		Tags: &[]sw.Tag{sw.Tag{Id: sw.PtrInt64(1), Name: sw.PtrString("tag2")}}})
 
 	r, err := client.PetApi.AddPet(context.Background(), newPet)
@@ -72,8 +72,8 @@ func TestBasicAuth(t *testing.T) {
 		Password: "f4k3p455",
 	})
 
-	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: sw.PtrString("gopher"),
-		PhotoUrls: &[]string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
+	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: "gopher",
+		PhotoUrls: []string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
 		Tags: &[]sw.Tag{sw.Tag{Id: sw.PtrInt64(1), Name: sw.PtrString("tag2")}}})
 
 	r, err := client.PetApi.AddPet(auth, newPet)
@@ -102,8 +102,8 @@ func TestBasicAuth(t *testing.T) {
 func TestAccessToken(t *testing.T) {
 	auth := context.WithValue(context.Background(), sw.ContextAccessToken, "TESTFAKEACCESSTOKENISFAKE")
 
-	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: sw.PtrString("gopher"),
-		PhotoUrls: &[]string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
+	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: "gopher",
+		PhotoUrls: []string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
 		Tags: &[]sw.Tag{sw.Tag{Id: sw.PtrInt64(1), Name: sw.PtrString("tag2")}}})
 
 	r, err := client.PetApi.AddPet(nil, newPet)
@@ -132,8 +132,8 @@ func TestAccessToken(t *testing.T) {
 func TestAPIKeyNoPrefix(t *testing.T) {
 	auth := context.WithValue(context.Background(), sw.ContextAPIKeys, map[string]sw.APIKey{"api_key": sw.APIKey{Key: "TEST123"}})
 
-	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: sw.PtrString("gopher"),
-		PhotoUrls: &[]string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
+	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: "gopher",
+		PhotoUrls: []string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
 		Tags: &[]sw.Tag{sw.Tag{Id: sw.PtrInt64(1), Name: sw.PtrString("tag2")}}})
 
 	r, err := client.PetApi.AddPet(context.Background(), newPet)
@@ -167,8 +167,8 @@ func TestAPIKeyNoPrefix(t *testing.T) {
 func TestAPIKeyWithPrefix(t *testing.T) {
 	auth := context.WithValue(context.Background(), sw.ContextAPIKeys, map[string]sw.APIKey{"api_key": sw.APIKey{Key: "TEST123", Prefix: "Bearer"}})
 
-	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: sw.PtrString("gopher"),
-		PhotoUrls: &[]string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
+	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: "gopher",
+		PhotoUrls: []string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
 		Tags: &[]sw.Tag{sw.Tag{Id: sw.PtrInt64(1), Name: sw.PtrString("tag2")}}})
 
 	r, err := client.PetApi.AddPet(nil, newPet)
@@ -200,9 +200,8 @@ func TestAPIKeyWithPrefix(t *testing.T) {
 }
 
 func TestDefaultHeader(t *testing.T) {
-
-	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: sw.PtrString("gopher"),
-		PhotoUrls: &[]string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
+	newPet := (sw.Pet{Id: sw.PtrInt64(12992), Name: "gopher",
+		PhotoUrls: []string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
 		Tags: &[]sw.Tag{sw.Tag{Id: sw.PtrInt64(1), Name: sw.PtrString("tag2")}}})
 
 	r, err := client.PetApi.AddPet(context.Background(), newPet)
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_200_response.go b/samples/client/petstore/go-experimental/go-petstore/model_200_response.go
index cebe724d060e..6aa7f9b6a79e 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_200_response.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_200_response.go
@@ -8,18 +8,19 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // Model200Response Model for testing model name starting with number
 type Model200Response struct {
 	Name *int32 `json:"name,omitempty"`
-
 	Class *string `json:"class,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *Model200Response) GetName() int32 {
 	if o == nil || o.Name == nil {
 		var ret int32
@@ -28,7 +29,7 @@ func (o *Model200Response) GetName() int32 {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Model200Response) GetNameOk() (int32, bool) {
 	if o == nil || o.Name == nil {
@@ -52,7 +53,7 @@ func (o *Model200Response) SetName(v int32) {
 	o.Name = &v
 }
 
-// GetClass returns the Class field if non-nil, zero value otherwise.
+// GetClass returns the Class field value if set, zero value otherwise.
 func (o *Model200Response) GetClass() string {
 	if o == nil || o.Class == nil {
 		var ret string
@@ -61,7 +62,7 @@ func (o *Model200Response) GetClass() string {
 	return *o.Class
 }
 
-// GetClassOk returns a tuple with the Class field if it's non-nil, zero value otherwise
+// GetClassOk returns a tuple with the Class field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Model200Response) GetClassOk() (string, bool) {
 	if o == nil || o.Class == nil {
@@ -85,17 +86,26 @@ func (o *Model200Response) SetClass(v string) {
 	o.Class = &v
 }
 
+type NullableModel200Response struct {
+	Value Model200Response
+	ExplicitNull bool
+}
+
+func (v NullableModel200Response) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Model200Response) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
-	}
-	if o.Class != nil {
-		toSerialize["class"] = o.Class
+func (v *NullableModel200Response) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_any_type.go b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_any_type.go
index 586b84f029b6..c6fbcc703b3c 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_any_type.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_any_type.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // AdditionalPropertiesAnyType struct for AdditionalPropertiesAnyType
 type AdditionalPropertiesAnyType struct {
 	Name *string `json:"name,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *AdditionalPropertiesAnyType) GetName() string {
 	if o == nil || o.Name == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *AdditionalPropertiesAnyType) GetName() string {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesAnyType) GetNameOk() (string, bool) {
 	if o == nil || o.Name == nil {
@@ -50,14 +52,26 @@ func (o *AdditionalPropertiesAnyType) SetName(v string) {
 	o.Name = &v
 }
 
+type NullableAdditionalPropertiesAnyType struct {
+	Value AdditionalPropertiesAnyType
+	ExplicitNull bool
+}
+
+func (v NullableAdditionalPropertiesAnyType) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o AdditionalPropertiesAnyType) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableAdditionalPropertiesAnyType) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_array.go b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_array.go
index 8cda0b7d08da..b1bf7f332828 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_array.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_array.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // AdditionalPropertiesArray struct for AdditionalPropertiesArray
 type AdditionalPropertiesArray struct {
 	Name *string `json:"name,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *AdditionalPropertiesArray) GetName() string {
 	if o == nil || o.Name == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *AdditionalPropertiesArray) GetName() string {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesArray) GetNameOk() (string, bool) {
 	if o == nil || o.Name == nil {
@@ -50,14 +52,26 @@ func (o *AdditionalPropertiesArray) SetName(v string) {
 	o.Name = &v
 }
 
+type NullableAdditionalPropertiesArray struct {
+	Value AdditionalPropertiesArray
+	ExplicitNull bool
+}
+
+func (v NullableAdditionalPropertiesArray) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o AdditionalPropertiesArray) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableAdditionalPropertiesArray) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_boolean.go b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_boolean.go
index 0148cce9ab42..c1aacbc1eb51 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_boolean.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_boolean.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // AdditionalPropertiesBoolean struct for AdditionalPropertiesBoolean
 type AdditionalPropertiesBoolean struct {
 	Name *string `json:"name,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *AdditionalPropertiesBoolean) GetName() string {
 	if o == nil || o.Name == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *AdditionalPropertiesBoolean) GetName() string {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesBoolean) GetNameOk() (string, bool) {
 	if o == nil || o.Name == nil {
@@ -50,14 +52,26 @@ func (o *AdditionalPropertiesBoolean) SetName(v string) {
 	o.Name = &v
 }
 
+type NullableAdditionalPropertiesBoolean struct {
+	Value AdditionalPropertiesBoolean
+	ExplicitNull bool
+}
+
+func (v NullableAdditionalPropertiesBoolean) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o AdditionalPropertiesBoolean) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableAdditionalPropertiesBoolean) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_class.go b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_class.go
index 6d9025a8965b..3c1e8db6244f 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_class.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_class.go
@@ -8,36 +8,28 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // AdditionalPropertiesClass struct for AdditionalPropertiesClass
 type AdditionalPropertiesClass struct {
 	MapString *map[string]string `json:"map_string,omitempty"`
-
 	MapNumber *map[string]float32 `json:"map_number,omitempty"`
-
 	MapInteger *map[string]int32 `json:"map_integer,omitempty"`
-
 	MapBoolean *map[string]bool `json:"map_boolean,omitempty"`
-
 	MapArrayInteger *map[string][]int32 `json:"map_array_integer,omitempty"`
-
 	MapArrayAnytype *map[string][]map[string]interface{} `json:"map_array_anytype,omitempty"`
-
 	MapMapString *map[string]map[string]string `json:"map_map_string,omitempty"`
-
 	MapMapAnytype *map[string]map[string]map[string]interface{} `json:"map_map_anytype,omitempty"`
-
 	Anytype1 *map[string]interface{} `json:"anytype_1,omitempty"`
-
 	Anytype2 *map[string]interface{} `json:"anytype_2,omitempty"`
-
 	Anytype3 *map[string]interface{} `json:"anytype_3,omitempty"`
-
 }
 
-// GetMapString returns the MapString field if non-nil, zero value otherwise.
+// GetMapString returns the MapString field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetMapString() map[string]string {
 	if o == nil || o.MapString == nil {
 		var ret map[string]string
@@ -46,7 +38,7 @@ func (o *AdditionalPropertiesClass) GetMapString() map[string]string {
 	return *o.MapString
 }
 
-// GetMapStringOk returns a tuple with the MapString field if it's non-nil, zero value otherwise
+// GetMapStringOk returns a tuple with the MapString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetMapStringOk() (map[string]string, bool) {
 	if o == nil || o.MapString == nil {
@@ -70,7 +62,7 @@ func (o *AdditionalPropertiesClass) SetMapString(v map[string]string) {
 	o.MapString = &v
 }
 
-// GetMapNumber returns the MapNumber field if non-nil, zero value otherwise.
+// GetMapNumber returns the MapNumber field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetMapNumber() map[string]float32 {
 	if o == nil || o.MapNumber == nil {
 		var ret map[string]float32
@@ -79,7 +71,7 @@ func (o *AdditionalPropertiesClass) GetMapNumber() map[string]float32 {
 	return *o.MapNumber
 }
 
-// GetMapNumberOk returns a tuple with the MapNumber field if it's non-nil, zero value otherwise
+// GetMapNumberOk returns a tuple with the MapNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetMapNumberOk() (map[string]float32, bool) {
 	if o == nil || o.MapNumber == nil {
@@ -103,7 +95,7 @@ func (o *AdditionalPropertiesClass) SetMapNumber(v map[string]float32) {
 	o.MapNumber = &v
 }
 
-// GetMapInteger returns the MapInteger field if non-nil, zero value otherwise.
+// GetMapInteger returns the MapInteger field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetMapInteger() map[string]int32 {
 	if o == nil || o.MapInteger == nil {
 		var ret map[string]int32
@@ -112,7 +104,7 @@ func (o *AdditionalPropertiesClass) GetMapInteger() map[string]int32 {
 	return *o.MapInteger
 }
 
-// GetMapIntegerOk returns a tuple with the MapInteger field if it's non-nil, zero value otherwise
+// GetMapIntegerOk returns a tuple with the MapInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetMapIntegerOk() (map[string]int32, bool) {
 	if o == nil || o.MapInteger == nil {
@@ -136,7 +128,7 @@ func (o *AdditionalPropertiesClass) SetMapInteger(v map[string]int32) {
 	o.MapInteger = &v
 }
 
-// GetMapBoolean returns the MapBoolean field if non-nil, zero value otherwise.
+// GetMapBoolean returns the MapBoolean field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetMapBoolean() map[string]bool {
 	if o == nil || o.MapBoolean == nil {
 		var ret map[string]bool
@@ -145,7 +137,7 @@ func (o *AdditionalPropertiesClass) GetMapBoolean() map[string]bool {
 	return *o.MapBoolean
 }
 
-// GetMapBooleanOk returns a tuple with the MapBoolean field if it's non-nil, zero value otherwise
+// GetMapBooleanOk returns a tuple with the MapBoolean field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetMapBooleanOk() (map[string]bool, bool) {
 	if o == nil || o.MapBoolean == nil {
@@ -169,7 +161,7 @@ func (o *AdditionalPropertiesClass) SetMapBoolean(v map[string]bool) {
 	o.MapBoolean = &v
 }
 
-// GetMapArrayInteger returns the MapArrayInteger field if non-nil, zero value otherwise.
+// GetMapArrayInteger returns the MapArrayInteger field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetMapArrayInteger() map[string][]int32 {
 	if o == nil || o.MapArrayInteger == nil {
 		var ret map[string][]int32
@@ -178,7 +170,7 @@ func (o *AdditionalPropertiesClass) GetMapArrayInteger() map[string][]int32 {
 	return *o.MapArrayInteger
 }
 
-// GetMapArrayIntegerOk returns a tuple with the MapArrayInteger field if it's non-nil, zero value otherwise
+// GetMapArrayIntegerOk returns a tuple with the MapArrayInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetMapArrayIntegerOk() (map[string][]int32, bool) {
 	if o == nil || o.MapArrayInteger == nil {
@@ -202,7 +194,7 @@ func (o *AdditionalPropertiesClass) SetMapArrayInteger(v map[string][]int32) {
 	o.MapArrayInteger = &v
 }
 
-// GetMapArrayAnytype returns the MapArrayAnytype field if non-nil, zero value otherwise.
+// GetMapArrayAnytype returns the MapArrayAnytype field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetMapArrayAnytype() map[string][]map[string]interface{} {
 	if o == nil || o.MapArrayAnytype == nil {
 		var ret map[string][]map[string]interface{}
@@ -211,7 +203,7 @@ func (o *AdditionalPropertiesClass) GetMapArrayAnytype() map[string][]map[string
 	return *o.MapArrayAnytype
 }
 
-// GetMapArrayAnytypeOk returns a tuple with the MapArrayAnytype field if it's non-nil, zero value otherwise
+// GetMapArrayAnytypeOk returns a tuple with the MapArrayAnytype field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetMapArrayAnytypeOk() (map[string][]map[string]interface{}, bool) {
 	if o == nil || o.MapArrayAnytype == nil {
@@ -235,7 +227,7 @@ func (o *AdditionalPropertiesClass) SetMapArrayAnytype(v map[string][]map[string
 	o.MapArrayAnytype = &v
 }
 
-// GetMapMapString returns the MapMapString field if non-nil, zero value otherwise.
+// GetMapMapString returns the MapMapString field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetMapMapString() map[string]map[string]string {
 	if o == nil || o.MapMapString == nil {
 		var ret map[string]map[string]string
@@ -244,7 +236,7 @@ func (o *AdditionalPropertiesClass) GetMapMapString() map[string]map[string]stri
 	return *o.MapMapString
 }
 
-// GetMapMapStringOk returns a tuple with the MapMapString field if it's non-nil, zero value otherwise
+// GetMapMapStringOk returns a tuple with the MapMapString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetMapMapStringOk() (map[string]map[string]string, bool) {
 	if o == nil || o.MapMapString == nil {
@@ -268,7 +260,7 @@ func (o *AdditionalPropertiesClass) SetMapMapString(v map[string]map[string]stri
 	o.MapMapString = &v
 }
 
-// GetMapMapAnytype returns the MapMapAnytype field if non-nil, zero value otherwise.
+// GetMapMapAnytype returns the MapMapAnytype field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetMapMapAnytype() map[string]map[string]map[string]interface{} {
 	if o == nil || o.MapMapAnytype == nil {
 		var ret map[string]map[string]map[string]interface{}
@@ -277,7 +269,7 @@ func (o *AdditionalPropertiesClass) GetMapMapAnytype() map[string]map[string]map
 	return *o.MapMapAnytype
 }
 
-// GetMapMapAnytypeOk returns a tuple with the MapMapAnytype field if it's non-nil, zero value otherwise
+// GetMapMapAnytypeOk returns a tuple with the MapMapAnytype field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetMapMapAnytypeOk() (map[string]map[string]map[string]interface{}, bool) {
 	if o == nil || o.MapMapAnytype == nil {
@@ -301,7 +293,7 @@ func (o *AdditionalPropertiesClass) SetMapMapAnytype(v map[string]map[string]map
 	o.MapMapAnytype = &v
 }
 
-// GetAnytype1 returns the Anytype1 field if non-nil, zero value otherwise.
+// GetAnytype1 returns the Anytype1 field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetAnytype1() map[string]interface{} {
 	if o == nil || o.Anytype1 == nil {
 		var ret map[string]interface{}
@@ -310,7 +302,7 @@ func (o *AdditionalPropertiesClass) GetAnytype1() map[string]interface{} {
 	return *o.Anytype1
 }
 
-// GetAnytype1Ok returns a tuple with the Anytype1 field if it's non-nil, zero value otherwise
+// GetAnytype1Ok returns a tuple with the Anytype1 field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetAnytype1Ok() (map[string]interface{}, bool) {
 	if o == nil || o.Anytype1 == nil {
@@ -334,7 +326,7 @@ func (o *AdditionalPropertiesClass) SetAnytype1(v map[string]interface{}) {
 	o.Anytype1 = &v
 }
 
-// GetAnytype2 returns the Anytype2 field if non-nil, zero value otherwise.
+// GetAnytype2 returns the Anytype2 field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetAnytype2() map[string]interface{} {
 	if o == nil || o.Anytype2 == nil {
 		var ret map[string]interface{}
@@ -343,7 +335,7 @@ func (o *AdditionalPropertiesClass) GetAnytype2() map[string]interface{} {
 	return *o.Anytype2
 }
 
-// GetAnytype2Ok returns a tuple with the Anytype2 field if it's non-nil, zero value otherwise
+// GetAnytype2Ok returns a tuple with the Anytype2 field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetAnytype2Ok() (map[string]interface{}, bool) {
 	if o == nil || o.Anytype2 == nil {
@@ -367,7 +359,7 @@ func (o *AdditionalPropertiesClass) SetAnytype2(v map[string]interface{}) {
 	o.Anytype2 = &v
 }
 
-// GetAnytype3 returns the Anytype3 field if non-nil, zero value otherwise.
+// GetAnytype3 returns the Anytype3 field value if set, zero value otherwise.
 func (o *AdditionalPropertiesClass) GetAnytype3() map[string]interface{} {
 	if o == nil || o.Anytype3 == nil {
 		var ret map[string]interface{}
@@ -376,7 +368,7 @@ func (o *AdditionalPropertiesClass) GetAnytype3() map[string]interface{} {
 	return *o.Anytype3
 }
 
-// GetAnytype3Ok returns a tuple with the Anytype3 field if it's non-nil, zero value otherwise
+// GetAnytype3Ok returns a tuple with the Anytype3 field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesClass) GetAnytype3Ok() (map[string]interface{}, bool) {
 	if o == nil || o.Anytype3 == nil {
@@ -400,44 +392,26 @@ func (o *AdditionalPropertiesClass) SetAnytype3(v map[string]interface{}) {
 	o.Anytype3 = &v
 }
 
+type NullableAdditionalPropertiesClass struct {
+	Value AdditionalPropertiesClass
+	ExplicitNull bool
+}
+
+func (v NullableAdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o AdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.MapString != nil {
-		toSerialize["map_string"] = o.MapString
-	}
-	if o.MapNumber != nil {
-		toSerialize["map_number"] = o.MapNumber
-	}
-	if o.MapInteger != nil {
-		toSerialize["map_integer"] = o.MapInteger
-	}
-	if o.MapBoolean != nil {
-		toSerialize["map_boolean"] = o.MapBoolean
-	}
-	if o.MapArrayInteger != nil {
-		toSerialize["map_array_integer"] = o.MapArrayInteger
-	}
-	if o.MapArrayAnytype != nil {
-		toSerialize["map_array_anytype"] = o.MapArrayAnytype
+func (v *NullableAdditionalPropertiesClass) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.MapMapString != nil {
-		toSerialize["map_map_string"] = o.MapMapString
-	}
-	if o.MapMapAnytype != nil {
-		toSerialize["map_map_anytype"] = o.MapMapAnytype
-	}
-	if o.Anytype1 != nil {
-		toSerialize["anytype_1"] = o.Anytype1
-	}
-	if o.Anytype2 != nil {
-		toSerialize["anytype_2"] = o.Anytype2
-	}
-	if o.Anytype3 != nil {
-		toSerialize["anytype_3"] = o.Anytype3
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_integer.go b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_integer.go
index c779aa63676c..07c11d9cdcd0 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_integer.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_integer.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // AdditionalPropertiesInteger struct for AdditionalPropertiesInteger
 type AdditionalPropertiesInteger struct {
 	Name *string `json:"name,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *AdditionalPropertiesInteger) GetName() string {
 	if o == nil || o.Name == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *AdditionalPropertiesInteger) GetName() string {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesInteger) GetNameOk() (string, bool) {
 	if o == nil || o.Name == nil {
@@ -50,14 +52,26 @@ func (o *AdditionalPropertiesInteger) SetName(v string) {
 	o.Name = &v
 }
 
+type NullableAdditionalPropertiesInteger struct {
+	Value AdditionalPropertiesInteger
+	ExplicitNull bool
+}
+
+func (v NullableAdditionalPropertiesInteger) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o AdditionalPropertiesInteger) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableAdditionalPropertiesInteger) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_number.go b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_number.go
index c14902300c67..59759fb409ee 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_number.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_number.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // AdditionalPropertiesNumber struct for AdditionalPropertiesNumber
 type AdditionalPropertiesNumber struct {
 	Name *string `json:"name,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *AdditionalPropertiesNumber) GetName() string {
 	if o == nil || o.Name == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *AdditionalPropertiesNumber) GetName() string {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesNumber) GetNameOk() (string, bool) {
 	if o == nil || o.Name == nil {
@@ -50,14 +52,26 @@ func (o *AdditionalPropertiesNumber) SetName(v string) {
 	o.Name = &v
 }
 
+type NullableAdditionalPropertiesNumber struct {
+	Value AdditionalPropertiesNumber
+	ExplicitNull bool
+}
+
+func (v NullableAdditionalPropertiesNumber) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o AdditionalPropertiesNumber) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableAdditionalPropertiesNumber) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_object.go b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_object.go
index 3fafb78aec03..df2b0305a4d5 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_object.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_object.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // AdditionalPropertiesObject struct for AdditionalPropertiesObject
 type AdditionalPropertiesObject struct {
 	Name *string `json:"name,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *AdditionalPropertiesObject) GetName() string {
 	if o == nil || o.Name == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *AdditionalPropertiesObject) GetName() string {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesObject) GetNameOk() (string, bool) {
 	if o == nil || o.Name == nil {
@@ -50,14 +52,26 @@ func (o *AdditionalPropertiesObject) SetName(v string) {
 	o.Name = &v
 }
 
+type NullableAdditionalPropertiesObject struct {
+	Value AdditionalPropertiesObject
+	ExplicitNull bool
+}
+
+func (v NullableAdditionalPropertiesObject) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o AdditionalPropertiesObject) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableAdditionalPropertiesObject) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_string.go b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_string.go
index bc75e98add3a..47eb4dd0de5e 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_string.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_additional_properties_string.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // AdditionalPropertiesString struct for AdditionalPropertiesString
 type AdditionalPropertiesString struct {
 	Name *string `json:"name,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *AdditionalPropertiesString) GetName() string {
 	if o == nil || o.Name == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *AdditionalPropertiesString) GetName() string {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *AdditionalPropertiesString) GetNameOk() (string, bool) {
 	if o == nil || o.Name == nil {
@@ -50,14 +52,26 @@ func (o *AdditionalPropertiesString) SetName(v string) {
 	o.Name = &v
 }
 
+type NullableAdditionalPropertiesString struct {
+	Value AdditionalPropertiesString
+	ExplicitNull bool
+}
+
+func (v NullableAdditionalPropertiesString) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o AdditionalPropertiesString) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableAdditionalPropertiesString) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_animal.go b/samples/client/petstore/go-experimental/go-petstore/model_animal.go
index 877476882ed5..dfae59606ed3 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_animal.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_animal.go
@@ -8,52 +8,34 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // Animal struct for Animal
 type Animal struct {
-	ClassName *string `json:"className,omitempty"`
-
+	ClassName string `json:"className"`
 	Color *string `json:"color,omitempty"`
-
 }
 
-// GetClassName returns the ClassName field if non-nil, zero value otherwise.
+// GetClassName returns the ClassName field value
 func (o *Animal) GetClassName() string {
-	if o == nil || o.ClassName == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.ClassName
-}
-
-// GetClassNameOk returns a tuple with the ClassName field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *Animal) GetClassNameOk() (string, bool) {
-	if o == nil || o.ClassName == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.ClassName, true
-}
-
-// HasClassName returns a boolean if a field has been set.
-func (o *Animal) HasClassName() bool {
-	if o != nil && o.ClassName != nil {
-		return true
-	}
 
-	return false
+	return o.ClassName
 }
 
-// SetClassName gets a reference to the given string and assigns it to the ClassName field.
+// SetClassName sets field value
 func (o *Animal) SetClassName(v string) {
-	o.ClassName = &v
+	o.ClassName = v
 }
 
-// GetColor returns the Color field if non-nil, zero value otherwise.
+// GetColor returns the Color field value if set, zero value otherwise.
 func (o *Animal) GetColor() string {
 	if o == nil || o.Color == nil {
 		var ret string
@@ -62,7 +44,7 @@ func (o *Animal) GetColor() string {
 	return *o.Color
 }
 
-// GetColorOk returns a tuple with the Color field if it's non-nil, zero value otherwise
+// GetColorOk returns a tuple with the Color field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Animal) GetColorOk() (string, bool) {
 	if o == nil || o.Color == nil {
@@ -86,20 +68,26 @@ func (o *Animal) SetColor(v string) {
 	o.Color = &v
 }
 
+type NullableAnimal struct {
+	Value Animal
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Animal) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.ClassName == nil {
-		return nil, errors.New("ClassName is required and not nullable, but was not set on Animal")
-	}
-	if o.ClassName != nil {
-		toSerialize["className"] = o.ClassName
-	}
-	if o.Color != nil {
-		toSerialize["color"] = o.Color
-	}
-	return json.Marshal(toSerialize)
+func (v NullableAnimal) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *NullableAnimal) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_api_response.go b/samples/client/petstore/go-experimental/go-petstore/model_api_response.go
index 358d4d4e569b..e2d80e220741 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_api_response.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_api_response.go
@@ -8,20 +8,20 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // ApiResponse struct for ApiResponse
 type ApiResponse struct {
 	Code *int32 `json:"code,omitempty"`
-
 	Type *string `json:"type,omitempty"`
-
 	Message *string `json:"message,omitempty"`
-
 }
 
-// GetCode returns the Code field if non-nil, zero value otherwise.
+// GetCode returns the Code field value if set, zero value otherwise.
 func (o *ApiResponse) GetCode() int32 {
 	if o == nil || o.Code == nil {
 		var ret int32
@@ -30,7 +30,7 @@ func (o *ApiResponse) GetCode() int32 {
 	return *o.Code
 }
 
-// GetCodeOk returns a tuple with the Code field if it's non-nil, zero value otherwise
+// GetCodeOk returns a tuple with the Code field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ApiResponse) GetCodeOk() (int32, bool) {
 	if o == nil || o.Code == nil {
@@ -54,7 +54,7 @@ func (o *ApiResponse) SetCode(v int32) {
 	o.Code = &v
 }
 
-// GetType returns the Type field if non-nil, zero value otherwise.
+// GetType returns the Type field value if set, zero value otherwise.
 func (o *ApiResponse) GetType() string {
 	if o == nil || o.Type == nil {
 		var ret string
@@ -63,7 +63,7 @@ func (o *ApiResponse) GetType() string {
 	return *o.Type
 }
 
-// GetTypeOk returns a tuple with the Type field if it's non-nil, zero value otherwise
+// GetTypeOk returns a tuple with the Type field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ApiResponse) GetTypeOk() (string, bool) {
 	if o == nil || o.Type == nil {
@@ -87,7 +87,7 @@ func (o *ApiResponse) SetType(v string) {
 	o.Type = &v
 }
 
-// GetMessage returns the Message field if non-nil, zero value otherwise.
+// GetMessage returns the Message field value if set, zero value otherwise.
 func (o *ApiResponse) GetMessage() string {
 	if o == nil || o.Message == nil {
 		var ret string
@@ -96,7 +96,7 @@ func (o *ApiResponse) GetMessage() string {
 	return *o.Message
 }
 
-// GetMessageOk returns a tuple with the Message field if it's non-nil, zero value otherwise
+// GetMessageOk returns a tuple with the Message field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ApiResponse) GetMessageOk() (string, bool) {
 	if o == nil || o.Message == nil {
@@ -120,20 +120,26 @@ func (o *ApiResponse) SetMessage(v string) {
 	o.Message = &v
 }
 
+type NullableApiResponse struct {
+	Value ApiResponse
+	ExplicitNull bool
+}
+
+func (v NullableApiResponse) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o ApiResponse) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Code != nil {
-		toSerialize["code"] = o.Code
-	}
-	if o.Type != nil {
-		toSerialize["type"] = o.Type
+func (v *NullableApiResponse) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.Message != nil {
-		toSerialize["message"] = o.Message
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_array_of_array_of_number_only.go b/samples/client/petstore/go-experimental/go-petstore/model_array_of_array_of_number_only.go
index de619c3fa055..cf5e59622f39 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_array_of_array_of_number_only.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_array_of_array_of_number_only.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // ArrayOfArrayOfNumberOnly struct for ArrayOfArrayOfNumberOnly
 type ArrayOfArrayOfNumberOnly struct {
 	ArrayArrayNumber *[][]float32 `json:"ArrayArrayNumber,omitempty"`
-
 }
 
-// GetArrayArrayNumber returns the ArrayArrayNumber field if non-nil, zero value otherwise.
+// GetArrayArrayNumber returns the ArrayArrayNumber field value if set, zero value otherwise.
 func (o *ArrayOfArrayOfNumberOnly) GetArrayArrayNumber() [][]float32 {
 	if o == nil || o.ArrayArrayNumber == nil {
 		var ret [][]float32
@@ -26,7 +28,7 @@ func (o *ArrayOfArrayOfNumberOnly) GetArrayArrayNumber() [][]float32 {
 	return *o.ArrayArrayNumber
 }
 
-// GetArrayArrayNumberOk returns a tuple with the ArrayArrayNumber field if it's non-nil, zero value otherwise
+// GetArrayArrayNumberOk returns a tuple with the ArrayArrayNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ArrayOfArrayOfNumberOnly) GetArrayArrayNumberOk() ([][]float32, bool) {
 	if o == nil || o.ArrayArrayNumber == nil {
@@ -50,14 +52,26 @@ func (o *ArrayOfArrayOfNumberOnly) SetArrayArrayNumber(v [][]float32) {
 	o.ArrayArrayNumber = &v
 }
 
+type NullableArrayOfArrayOfNumberOnly struct {
+	Value ArrayOfArrayOfNumberOnly
+	ExplicitNull bool
+}
+
+func (v NullableArrayOfArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o ArrayOfArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.ArrayArrayNumber != nil {
-		toSerialize["ArrayArrayNumber"] = o.ArrayArrayNumber
+func (v *NullableArrayOfArrayOfNumberOnly) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_array_of_number_only.go b/samples/client/petstore/go-experimental/go-petstore/model_array_of_number_only.go
index 4efd5be06039..7495577a4ce5 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_array_of_number_only.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_array_of_number_only.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // ArrayOfNumberOnly struct for ArrayOfNumberOnly
 type ArrayOfNumberOnly struct {
 	ArrayNumber *[]float32 `json:"ArrayNumber,omitempty"`
-
 }
 
-// GetArrayNumber returns the ArrayNumber field if non-nil, zero value otherwise.
+// GetArrayNumber returns the ArrayNumber field value if set, zero value otherwise.
 func (o *ArrayOfNumberOnly) GetArrayNumber() []float32 {
 	if o == nil || o.ArrayNumber == nil {
 		var ret []float32
@@ -26,7 +28,7 @@ func (o *ArrayOfNumberOnly) GetArrayNumber() []float32 {
 	return *o.ArrayNumber
 }
 
-// GetArrayNumberOk returns a tuple with the ArrayNumber field if it's non-nil, zero value otherwise
+// GetArrayNumberOk returns a tuple with the ArrayNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ArrayOfNumberOnly) GetArrayNumberOk() ([]float32, bool) {
 	if o == nil || o.ArrayNumber == nil {
@@ -50,14 +52,26 @@ func (o *ArrayOfNumberOnly) SetArrayNumber(v []float32) {
 	o.ArrayNumber = &v
 }
 
+type NullableArrayOfNumberOnly struct {
+	Value ArrayOfNumberOnly
+	ExplicitNull bool
+}
+
+func (v NullableArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o ArrayOfNumberOnly) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.ArrayNumber != nil {
-		toSerialize["ArrayNumber"] = o.ArrayNumber
+func (v *NullableArrayOfNumberOnly) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_array_test_.go b/samples/client/petstore/go-experimental/go-petstore/model_array_test_.go
index 2e1b18949dc2..01d310fd480a 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_array_test_.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_array_test_.go
@@ -8,20 +8,20 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // ArrayTest struct for ArrayTest
 type ArrayTest struct {
 	ArrayOfString *[]string `json:"array_of_string,omitempty"`
-
 	ArrayArrayOfInteger *[][]int64 `json:"array_array_of_integer,omitempty"`
-
 	ArrayArrayOfModel *[][]ReadOnlyFirst `json:"array_array_of_model,omitempty"`
-
 }
 
-// GetArrayOfString returns the ArrayOfString field if non-nil, zero value otherwise.
+// GetArrayOfString returns the ArrayOfString field value if set, zero value otherwise.
 func (o *ArrayTest) GetArrayOfString() []string {
 	if o == nil || o.ArrayOfString == nil {
 		var ret []string
@@ -30,7 +30,7 @@ func (o *ArrayTest) GetArrayOfString() []string {
 	return *o.ArrayOfString
 }
 
-// GetArrayOfStringOk returns a tuple with the ArrayOfString field if it's non-nil, zero value otherwise
+// GetArrayOfStringOk returns a tuple with the ArrayOfString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ArrayTest) GetArrayOfStringOk() ([]string, bool) {
 	if o == nil || o.ArrayOfString == nil {
@@ -54,7 +54,7 @@ func (o *ArrayTest) SetArrayOfString(v []string) {
 	o.ArrayOfString = &v
 }
 
-// GetArrayArrayOfInteger returns the ArrayArrayOfInteger field if non-nil, zero value otherwise.
+// GetArrayArrayOfInteger returns the ArrayArrayOfInteger field value if set, zero value otherwise.
 func (o *ArrayTest) GetArrayArrayOfInteger() [][]int64 {
 	if o == nil || o.ArrayArrayOfInteger == nil {
 		var ret [][]int64
@@ -63,7 +63,7 @@ func (o *ArrayTest) GetArrayArrayOfInteger() [][]int64 {
 	return *o.ArrayArrayOfInteger
 }
 
-// GetArrayArrayOfIntegerOk returns a tuple with the ArrayArrayOfInteger field if it's non-nil, zero value otherwise
+// GetArrayArrayOfIntegerOk returns a tuple with the ArrayArrayOfInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ArrayTest) GetArrayArrayOfIntegerOk() ([][]int64, bool) {
 	if o == nil || o.ArrayArrayOfInteger == nil {
@@ -87,7 +87,7 @@ func (o *ArrayTest) SetArrayArrayOfInteger(v [][]int64) {
 	o.ArrayArrayOfInteger = &v
 }
 
-// GetArrayArrayOfModel returns the ArrayArrayOfModel field if non-nil, zero value otherwise.
+// GetArrayArrayOfModel returns the ArrayArrayOfModel field value if set, zero value otherwise.
 func (o *ArrayTest) GetArrayArrayOfModel() [][]ReadOnlyFirst {
 	if o == nil || o.ArrayArrayOfModel == nil {
 		var ret [][]ReadOnlyFirst
@@ -96,7 +96,7 @@ func (o *ArrayTest) GetArrayArrayOfModel() [][]ReadOnlyFirst {
 	return *o.ArrayArrayOfModel
 }
 
-// GetArrayArrayOfModelOk returns a tuple with the ArrayArrayOfModel field if it's non-nil, zero value otherwise
+// GetArrayArrayOfModelOk returns a tuple with the ArrayArrayOfModel field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ArrayTest) GetArrayArrayOfModelOk() ([][]ReadOnlyFirst, bool) {
 	if o == nil || o.ArrayArrayOfModel == nil {
@@ -120,20 +120,26 @@ func (o *ArrayTest) SetArrayArrayOfModel(v [][]ReadOnlyFirst) {
 	o.ArrayArrayOfModel = &v
 }
 
+type NullableArrayTest struct {
+	Value ArrayTest
+	ExplicitNull bool
+}
+
+func (v NullableArrayTest) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o ArrayTest) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.ArrayOfString != nil {
-		toSerialize["array_of_string"] = o.ArrayOfString
-	}
-	if o.ArrayArrayOfInteger != nil {
-		toSerialize["array_array_of_integer"] = o.ArrayArrayOfInteger
+func (v *NullableArrayTest) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.ArrayArrayOfModel != nil {
-		toSerialize["array_array_of_model"] = o.ArrayArrayOfModel
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_capitalization.go b/samples/client/petstore/go-experimental/go-petstore/model_capitalization.go
index 9cd486a70ca6..281f380508c3 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_capitalization.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_capitalization.go
@@ -8,27 +8,24 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // Capitalization struct for Capitalization
 type Capitalization struct {
 	SmallCamel *string `json:"smallCamel,omitempty"`
-
 	CapitalCamel *string `json:"CapitalCamel,omitempty"`
-
 	SmallSnake *string `json:"small_Snake,omitempty"`
-
 	CapitalSnake *string `json:"Capital_Snake,omitempty"`
-
 	SCAETHFlowPoints *string `json:"SCA_ETH_Flow_Points,omitempty"`
-
 	// Name of the pet 
 	ATT_NAME *string `json:"ATT_NAME,omitempty"`
-
 }
 
-// GetSmallCamel returns the SmallCamel field if non-nil, zero value otherwise.
+// GetSmallCamel returns the SmallCamel field value if set, zero value otherwise.
 func (o *Capitalization) GetSmallCamel() string {
 	if o == nil || o.SmallCamel == nil {
 		var ret string
@@ -37,7 +34,7 @@ func (o *Capitalization) GetSmallCamel() string {
 	return *o.SmallCamel
 }
 
-// GetSmallCamelOk returns a tuple with the SmallCamel field if it's non-nil, zero value otherwise
+// GetSmallCamelOk returns a tuple with the SmallCamel field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Capitalization) GetSmallCamelOk() (string, bool) {
 	if o == nil || o.SmallCamel == nil {
@@ -61,7 +58,7 @@ func (o *Capitalization) SetSmallCamel(v string) {
 	o.SmallCamel = &v
 }
 
-// GetCapitalCamel returns the CapitalCamel field if non-nil, zero value otherwise.
+// GetCapitalCamel returns the CapitalCamel field value if set, zero value otherwise.
 func (o *Capitalization) GetCapitalCamel() string {
 	if o == nil || o.CapitalCamel == nil {
 		var ret string
@@ -70,7 +67,7 @@ func (o *Capitalization) GetCapitalCamel() string {
 	return *o.CapitalCamel
 }
 
-// GetCapitalCamelOk returns a tuple with the CapitalCamel field if it's non-nil, zero value otherwise
+// GetCapitalCamelOk returns a tuple with the CapitalCamel field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Capitalization) GetCapitalCamelOk() (string, bool) {
 	if o == nil || o.CapitalCamel == nil {
@@ -94,7 +91,7 @@ func (o *Capitalization) SetCapitalCamel(v string) {
 	o.CapitalCamel = &v
 }
 
-// GetSmallSnake returns the SmallSnake field if non-nil, zero value otherwise.
+// GetSmallSnake returns the SmallSnake field value if set, zero value otherwise.
 func (o *Capitalization) GetSmallSnake() string {
 	if o == nil || o.SmallSnake == nil {
 		var ret string
@@ -103,7 +100,7 @@ func (o *Capitalization) GetSmallSnake() string {
 	return *o.SmallSnake
 }
 
-// GetSmallSnakeOk returns a tuple with the SmallSnake field if it's non-nil, zero value otherwise
+// GetSmallSnakeOk returns a tuple with the SmallSnake field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Capitalization) GetSmallSnakeOk() (string, bool) {
 	if o == nil || o.SmallSnake == nil {
@@ -127,7 +124,7 @@ func (o *Capitalization) SetSmallSnake(v string) {
 	o.SmallSnake = &v
 }
 
-// GetCapitalSnake returns the CapitalSnake field if non-nil, zero value otherwise.
+// GetCapitalSnake returns the CapitalSnake field value if set, zero value otherwise.
 func (o *Capitalization) GetCapitalSnake() string {
 	if o == nil || o.CapitalSnake == nil {
 		var ret string
@@ -136,7 +133,7 @@ func (o *Capitalization) GetCapitalSnake() string {
 	return *o.CapitalSnake
 }
 
-// GetCapitalSnakeOk returns a tuple with the CapitalSnake field if it's non-nil, zero value otherwise
+// GetCapitalSnakeOk returns a tuple with the CapitalSnake field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Capitalization) GetCapitalSnakeOk() (string, bool) {
 	if o == nil || o.CapitalSnake == nil {
@@ -160,7 +157,7 @@ func (o *Capitalization) SetCapitalSnake(v string) {
 	o.CapitalSnake = &v
 }
 
-// GetSCAETHFlowPoints returns the SCAETHFlowPoints field if non-nil, zero value otherwise.
+// GetSCAETHFlowPoints returns the SCAETHFlowPoints field value if set, zero value otherwise.
 func (o *Capitalization) GetSCAETHFlowPoints() string {
 	if o == nil || o.SCAETHFlowPoints == nil {
 		var ret string
@@ -169,7 +166,7 @@ func (o *Capitalization) GetSCAETHFlowPoints() string {
 	return *o.SCAETHFlowPoints
 }
 
-// GetSCAETHFlowPointsOk returns a tuple with the SCAETHFlowPoints field if it's non-nil, zero value otherwise
+// GetSCAETHFlowPointsOk returns a tuple with the SCAETHFlowPoints field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Capitalization) GetSCAETHFlowPointsOk() (string, bool) {
 	if o == nil || o.SCAETHFlowPoints == nil {
@@ -193,7 +190,7 @@ func (o *Capitalization) SetSCAETHFlowPoints(v string) {
 	o.SCAETHFlowPoints = &v
 }
 
-// GetATT_NAME returns the ATT_NAME field if non-nil, zero value otherwise.
+// GetATT_NAME returns the ATT_NAME field value if set, zero value otherwise.
 func (o *Capitalization) GetATT_NAME() string {
 	if o == nil || o.ATT_NAME == nil {
 		var ret string
@@ -202,7 +199,7 @@ func (o *Capitalization) GetATT_NAME() string {
 	return *o.ATT_NAME
 }
 
-// GetATT_NAMEOk returns a tuple with the ATT_NAME field if it's non-nil, zero value otherwise
+// GetATT_NAMEOk returns a tuple with the ATT_NAME field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Capitalization) GetATT_NAMEOk() (string, bool) {
 	if o == nil || o.ATT_NAME == nil {
@@ -226,29 +223,26 @@ func (o *Capitalization) SetATT_NAME(v string) {
 	o.ATT_NAME = &v
 }
 
+type NullableCapitalization struct {
+	Value Capitalization
+	ExplicitNull bool
+}
+
+func (v NullableCapitalization) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Capitalization) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.SmallCamel != nil {
-		toSerialize["smallCamel"] = o.SmallCamel
-	}
-	if o.CapitalCamel != nil {
-		toSerialize["CapitalCamel"] = o.CapitalCamel
-	}
-	if o.SmallSnake != nil {
-		toSerialize["small_Snake"] = o.SmallSnake
-	}
-	if o.CapitalSnake != nil {
-		toSerialize["Capital_Snake"] = o.CapitalSnake
+func (v *NullableCapitalization) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.SCAETHFlowPoints != nil {
-		toSerialize["SCA_ETH_Flow_Points"] = o.SCAETHFlowPoints
-	}
-	if o.ATT_NAME != nil {
-		toSerialize["ATT_NAME"] = o.ATT_NAME
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_cat.go b/samples/client/petstore/go-experimental/go-petstore/model_cat.go
index 07dfafae8b65..a4390348e393 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_cat.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_cat.go
@@ -8,54 +8,35 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // Cat struct for Cat
 type Cat struct {
-	ClassName *string `json:"className,omitempty"`
-
+	ClassName string `json:"className"`
 	Color *string `json:"color,omitempty"`
-
 	Declawed *bool `json:"declawed,omitempty"`
-
 }
 
-// GetClassName returns the ClassName field if non-nil, zero value otherwise.
+// GetClassName returns the ClassName field value
 func (o *Cat) GetClassName() string {
-	if o == nil || o.ClassName == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.ClassName
-}
-
-// GetClassNameOk returns a tuple with the ClassName field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *Cat) GetClassNameOk() (string, bool) {
-	if o == nil || o.ClassName == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.ClassName, true
-}
-
-// HasClassName returns a boolean if a field has been set.
-func (o *Cat) HasClassName() bool {
-	if o != nil && o.ClassName != nil {
-		return true
-	}
 
-	return false
+	return o.ClassName
 }
 
-// SetClassName gets a reference to the given string and assigns it to the ClassName field.
+// SetClassName sets field value
 func (o *Cat) SetClassName(v string) {
-	o.ClassName = &v
+	o.ClassName = v
 }
 
-// GetColor returns the Color field if non-nil, zero value otherwise.
+// GetColor returns the Color field value if set, zero value otherwise.
 func (o *Cat) GetColor() string {
 	if o == nil || o.Color == nil {
 		var ret string
@@ -64,7 +45,7 @@ func (o *Cat) GetColor() string {
 	return *o.Color
 }
 
-// GetColorOk returns a tuple with the Color field if it's non-nil, zero value otherwise
+// GetColorOk returns a tuple with the Color field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Cat) GetColorOk() (string, bool) {
 	if o == nil || o.Color == nil {
@@ -88,7 +69,7 @@ func (o *Cat) SetColor(v string) {
 	o.Color = &v
 }
 
-// GetDeclawed returns the Declawed field if non-nil, zero value otherwise.
+// GetDeclawed returns the Declawed field value if set, zero value otherwise.
 func (o *Cat) GetDeclawed() bool {
 	if o == nil || o.Declawed == nil {
 		var ret bool
@@ -97,7 +78,7 @@ func (o *Cat) GetDeclawed() bool {
 	return *o.Declawed
 }
 
-// GetDeclawedOk returns a tuple with the Declawed field if it's non-nil, zero value otherwise
+// GetDeclawedOk returns a tuple with the Declawed field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Cat) GetDeclawedOk() (bool, bool) {
 	if o == nil || o.Declawed == nil {
@@ -121,23 +102,26 @@ func (o *Cat) SetDeclawed(v bool) {
 	o.Declawed = &v
 }
 
+type NullableCat struct {
+	Value Cat
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Cat) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.ClassName == nil {
-		return nil, errors.New("ClassName is required and not nullable, but was not set on Cat")
-	}
-	if o.ClassName != nil {
-		toSerialize["className"] = o.ClassName
-	}
-	if o.Color != nil {
-		toSerialize["color"] = o.Color
-	}
-	if o.Declawed != nil {
-		toSerialize["declawed"] = o.Declawed
-	}
-	return json.Marshal(toSerialize)
+func (v NullableCat) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *NullableCat) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_cat_all_of.go b/samples/client/petstore/go-experimental/go-petstore/model_cat_all_of.go
index db53c7dbbd6b..5fe06820a255 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_cat_all_of.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_cat_all_of.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // CatAllOf struct for CatAllOf
 type CatAllOf struct {
 	Declawed *bool `json:"declawed,omitempty"`
-
 }
 
-// GetDeclawed returns the Declawed field if non-nil, zero value otherwise.
+// GetDeclawed returns the Declawed field value if set, zero value otherwise.
 func (o *CatAllOf) GetDeclawed() bool {
 	if o == nil || o.Declawed == nil {
 		var ret bool
@@ -26,7 +28,7 @@ func (o *CatAllOf) GetDeclawed() bool {
 	return *o.Declawed
 }
 
-// GetDeclawedOk returns a tuple with the Declawed field if it's non-nil, zero value otherwise
+// GetDeclawedOk returns a tuple with the Declawed field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *CatAllOf) GetDeclawedOk() (bool, bool) {
 	if o == nil || o.Declawed == nil {
@@ -50,14 +52,26 @@ func (o *CatAllOf) SetDeclawed(v bool) {
 	o.Declawed = &v
 }
 
+type NullableCatAllOf struct {
+	Value CatAllOf
+	ExplicitNull bool
+}
+
+func (v NullableCatAllOf) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o CatAllOf) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Declawed != nil {
-		toSerialize["declawed"] = o.Declawed
+func (v *NullableCatAllOf) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_category.go b/samples/client/petstore/go-experimental/go-petstore/model_category.go
index eef9caf28f1f..1a4d80c25abf 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_category.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_category.go
@@ -8,19 +8,19 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // Category struct for Category
 type Category struct {
 	Id *int64 `json:"id,omitempty"`
-
-	Name *string `json:"name,omitempty"`
-
+	Name string `json:"name"`
 }
 
-// GetId returns the Id field if non-nil, zero value otherwise.
+// GetId returns the Id field value if set, zero value otherwise.
 func (o *Category) GetId() int64 {
 	if o == nil || o.Id == nil {
 		var ret int64
@@ -29,7 +29,7 @@ func (o *Category) GetId() int64 {
 	return *o.Id
 }
 
-// GetIdOk returns a tuple with the Id field if it's non-nil, zero value otherwise
+// GetIdOk returns a tuple with the Id field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Category) GetIdOk() (int64, bool) {
 	if o == nil || o.Id == nil {
@@ -53,53 +53,41 @@ func (o *Category) SetId(v int64) {
 	o.Id = &v
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value
 func (o *Category) GetName() string {
-	if o == nil || o.Name == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.Name
-}
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *Category) GetNameOk() (string, bool) {
-	if o == nil || o.Name == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.Name, true
+	return o.Name
 }
 
-// HasName returns a boolean if a field has been set.
-func (o *Category) HasName() bool {
-	if o != nil && o.Name != nil {
-		return true
-	}
-
-	return false
+// SetName sets field value
+func (o *Category) SetName(v string) {
+	o.Name = v
 }
 
-// SetName gets a reference to the given string and assigns it to the Name field.
-func (o *Category) SetName(v string) {
-	o.Name = &v
+type NullableCategory struct {
+	Value Category
+	ExplicitNull bool
 }
 
+func (v NullableCategory) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Category) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Id != nil {
-		toSerialize["id"] = o.Id
-	}
-	if o.Name == nil {
-		return nil, errors.New("Name is required and not nullable, but was not set on Category")
-	}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableCategory) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_class_model.go b/samples/client/petstore/go-experimental/go-petstore/model_class_model.go
index 8a83ac5698bd..cb217ea0b938 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_class_model.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_class_model.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // ClassModel Model for testing model with \"_class\" property
 type ClassModel struct {
 	Class *string `json:"_class,omitempty"`
-
 }
 
-// GetClass returns the Class field if non-nil, zero value otherwise.
+// GetClass returns the Class field value if set, zero value otherwise.
 func (o *ClassModel) GetClass() string {
 	if o == nil || o.Class == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *ClassModel) GetClass() string {
 	return *o.Class
 }
 
-// GetClassOk returns a tuple with the Class field if it's non-nil, zero value otherwise
+// GetClassOk returns a tuple with the Class field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ClassModel) GetClassOk() (string, bool) {
 	if o == nil || o.Class == nil {
@@ -50,14 +52,26 @@ func (o *ClassModel) SetClass(v string) {
 	o.Class = &v
 }
 
+type NullableClassModel struct {
+	Value ClassModel
+	ExplicitNull bool
+}
+
+func (v NullableClassModel) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o ClassModel) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Class != nil {
-		toSerialize["_class"] = o.Class
+func (v *NullableClassModel) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_client.go b/samples/client/petstore/go-experimental/go-petstore/model_client.go
index abead359c737..1c2d82dbaa25 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_client.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_client.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // Client struct for Client
 type Client struct {
 	Client *string `json:"client,omitempty"`
-
 }
 
-// GetClient returns the Client field if non-nil, zero value otherwise.
+// GetClient returns the Client field value if set, zero value otherwise.
 func (o *Client) GetClient() string {
 	if o == nil || o.Client == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *Client) GetClient() string {
 	return *o.Client
 }
 
-// GetClientOk returns a tuple with the Client field if it's non-nil, zero value otherwise
+// GetClientOk returns a tuple with the Client field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Client) GetClientOk() (string, bool) {
 	if o == nil || o.Client == nil {
@@ -50,14 +52,26 @@ func (o *Client) SetClient(v string) {
 	o.Client = &v
 }
 
+type NullableClient struct {
+	Value Client
+	ExplicitNull bool
+}
+
+func (v NullableClient) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Client) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Client != nil {
-		toSerialize["client"] = o.Client
+func (v *NullableClient) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_dog.go b/samples/client/petstore/go-experimental/go-petstore/model_dog.go
index 2c09989cca72..1e12cf2030e2 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_dog.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_dog.go
@@ -8,54 +8,35 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // Dog struct for Dog
 type Dog struct {
-	ClassName *string `json:"className,omitempty"`
-
+	ClassName string `json:"className"`
 	Color *string `json:"color,omitempty"`
-
 	Breed *string `json:"breed,omitempty"`
-
 }
 
-// GetClassName returns the ClassName field if non-nil, zero value otherwise.
+// GetClassName returns the ClassName field value
 func (o *Dog) GetClassName() string {
-	if o == nil || o.ClassName == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.ClassName
-}
-
-// GetClassNameOk returns a tuple with the ClassName field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *Dog) GetClassNameOk() (string, bool) {
-	if o == nil || o.ClassName == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.ClassName, true
-}
-
-// HasClassName returns a boolean if a field has been set.
-func (o *Dog) HasClassName() bool {
-	if o != nil && o.ClassName != nil {
-		return true
-	}
 
-	return false
+	return o.ClassName
 }
 
-// SetClassName gets a reference to the given string and assigns it to the ClassName field.
+// SetClassName sets field value
 func (o *Dog) SetClassName(v string) {
-	o.ClassName = &v
+	o.ClassName = v
 }
 
-// GetColor returns the Color field if non-nil, zero value otherwise.
+// GetColor returns the Color field value if set, zero value otherwise.
 func (o *Dog) GetColor() string {
 	if o == nil || o.Color == nil {
 		var ret string
@@ -64,7 +45,7 @@ func (o *Dog) GetColor() string {
 	return *o.Color
 }
 
-// GetColorOk returns a tuple with the Color field if it's non-nil, zero value otherwise
+// GetColorOk returns a tuple with the Color field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Dog) GetColorOk() (string, bool) {
 	if o == nil || o.Color == nil {
@@ -88,7 +69,7 @@ func (o *Dog) SetColor(v string) {
 	o.Color = &v
 }
 
-// GetBreed returns the Breed field if non-nil, zero value otherwise.
+// GetBreed returns the Breed field value if set, zero value otherwise.
 func (o *Dog) GetBreed() string {
 	if o == nil || o.Breed == nil {
 		var ret string
@@ -97,7 +78,7 @@ func (o *Dog) GetBreed() string {
 	return *o.Breed
 }
 
-// GetBreedOk returns a tuple with the Breed field if it's non-nil, zero value otherwise
+// GetBreedOk returns a tuple with the Breed field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Dog) GetBreedOk() (string, bool) {
 	if o == nil || o.Breed == nil {
@@ -121,23 +102,26 @@ func (o *Dog) SetBreed(v string) {
 	o.Breed = &v
 }
 
+type NullableDog struct {
+	Value Dog
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Dog) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.ClassName == nil {
-		return nil, errors.New("ClassName is required and not nullable, but was not set on Dog")
-	}
-	if o.ClassName != nil {
-		toSerialize["className"] = o.ClassName
-	}
-	if o.Color != nil {
-		toSerialize["color"] = o.Color
-	}
-	if o.Breed != nil {
-		toSerialize["breed"] = o.Breed
-	}
-	return json.Marshal(toSerialize)
+func (v NullableDog) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *NullableDog) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_dog_all_of.go b/samples/client/petstore/go-experimental/go-petstore/model_dog_all_of.go
index abd645b6e72d..0572953d4691 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_dog_all_of.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_dog_all_of.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // DogAllOf struct for DogAllOf
 type DogAllOf struct {
 	Breed *string `json:"breed,omitempty"`
-
 }
 
-// GetBreed returns the Breed field if non-nil, zero value otherwise.
+// GetBreed returns the Breed field value if set, zero value otherwise.
 func (o *DogAllOf) GetBreed() string {
 	if o == nil || o.Breed == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *DogAllOf) GetBreed() string {
 	return *o.Breed
 }
 
-// GetBreedOk returns a tuple with the Breed field if it's non-nil, zero value otherwise
+// GetBreedOk returns a tuple with the Breed field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *DogAllOf) GetBreedOk() (string, bool) {
 	if o == nil || o.Breed == nil {
@@ -50,14 +52,26 @@ func (o *DogAllOf) SetBreed(v string) {
 	o.Breed = &v
 }
 
+type NullableDogAllOf struct {
+	Value DogAllOf
+	ExplicitNull bool
+}
+
+func (v NullableDogAllOf) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o DogAllOf) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Breed != nil {
-		toSerialize["breed"] = o.Breed
+func (v *NullableDogAllOf) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_enum_arrays.go b/samples/client/petstore/go-experimental/go-petstore/model_enum_arrays.go
index 453848096d14..68b520550b3a 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_enum_arrays.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_enum_arrays.go
@@ -8,18 +8,19 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // EnumArrays struct for EnumArrays
 type EnumArrays struct {
 	JustSymbol *string `json:"just_symbol,omitempty"`
-
 	ArrayEnum *[]string `json:"array_enum,omitempty"`
-
 }
 
-// GetJustSymbol returns the JustSymbol field if non-nil, zero value otherwise.
+// GetJustSymbol returns the JustSymbol field value if set, zero value otherwise.
 func (o *EnumArrays) GetJustSymbol() string {
 	if o == nil || o.JustSymbol == nil {
 		var ret string
@@ -28,7 +29,7 @@ func (o *EnumArrays) GetJustSymbol() string {
 	return *o.JustSymbol
 }
 
-// GetJustSymbolOk returns a tuple with the JustSymbol field if it's non-nil, zero value otherwise
+// GetJustSymbolOk returns a tuple with the JustSymbol field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *EnumArrays) GetJustSymbolOk() (string, bool) {
 	if o == nil || o.JustSymbol == nil {
@@ -52,7 +53,7 @@ func (o *EnumArrays) SetJustSymbol(v string) {
 	o.JustSymbol = &v
 }
 
-// GetArrayEnum returns the ArrayEnum field if non-nil, zero value otherwise.
+// GetArrayEnum returns the ArrayEnum field value if set, zero value otherwise.
 func (o *EnumArrays) GetArrayEnum() []string {
 	if o == nil || o.ArrayEnum == nil {
 		var ret []string
@@ -61,7 +62,7 @@ func (o *EnumArrays) GetArrayEnum() []string {
 	return *o.ArrayEnum
 }
 
-// GetArrayEnumOk returns a tuple with the ArrayEnum field if it's non-nil, zero value otherwise
+// GetArrayEnumOk returns a tuple with the ArrayEnum field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *EnumArrays) GetArrayEnumOk() ([]string, bool) {
 	if o == nil || o.ArrayEnum == nil {
@@ -85,17 +86,26 @@ func (o *EnumArrays) SetArrayEnum(v []string) {
 	o.ArrayEnum = &v
 }
 
+type NullableEnumArrays struct {
+	Value EnumArrays
+	ExplicitNull bool
+}
+
+func (v NullableEnumArrays) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o EnumArrays) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.JustSymbol != nil {
-		toSerialize["just_symbol"] = o.JustSymbol
-	}
-	if o.ArrayEnum != nil {
-		toSerialize["array_enum"] = o.ArrayEnum
+func (v *NullableEnumArrays) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_enum_class.go b/samples/client/petstore/go-experimental/go-petstore/model_enum_class.go
index 06f7d5535ded..8864dc38698e 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_enum_class.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_enum_class.go
@@ -8,6 +8,12 @@
  */
 
 package petstore
+
+import (
+	"bytes"
+	"encoding/json"
+)
+
 // EnumClass the model 'EnumClass'
 type EnumClass string
 
@@ -18,4 +24,30 @@ const (
 	XYZ EnumClass = "(xyz)"
 )
 
+type NullableEnumClass struct {
+	Value EnumClass
+	ExplicitNull bool
+}
+
+func (v NullableEnumClass) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != "":
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
+
+func (v *NullableEnumClass) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
+
+
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_enum_test_.go b/samples/client/petstore/go-experimental/go-petstore/model_enum_test_.go
index 17a5fc44fd34..8594082a56ae 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_enum_test_.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_enum_test_.go
@@ -8,25 +8,22 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // EnumTest struct for EnumTest
 type EnumTest struct {
 	EnumString *string `json:"enum_string,omitempty"`
-
-	EnumStringRequired *string `json:"enum_string_required,omitempty"`
-
+	EnumStringRequired string `json:"enum_string_required"`
 	EnumInteger *int32 `json:"enum_integer,omitempty"`
-
 	EnumNumber *float64 `json:"enum_number,omitempty"`
-
 	OuterEnum *OuterEnum `json:"outerEnum,omitempty"`
-
 }
 
-// GetEnumString returns the EnumString field if non-nil, zero value otherwise.
+// GetEnumString returns the EnumString field value if set, zero value otherwise.
 func (o *EnumTest) GetEnumString() string {
 	if o == nil || o.EnumString == nil {
 		var ret string
@@ -35,7 +32,7 @@ func (o *EnumTest) GetEnumString() string {
 	return *o.EnumString
 }
 
-// GetEnumStringOk returns a tuple with the EnumString field if it's non-nil, zero value otherwise
+// GetEnumStringOk returns a tuple with the EnumString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *EnumTest) GetEnumStringOk() (string, bool) {
 	if o == nil || o.EnumString == nil {
@@ -59,40 +56,22 @@ func (o *EnumTest) SetEnumString(v string) {
 	o.EnumString = &v
 }
 
-// GetEnumStringRequired returns the EnumStringRequired field if non-nil, zero value otherwise.
+// GetEnumStringRequired returns the EnumStringRequired field value
 func (o *EnumTest) GetEnumStringRequired() string {
-	if o == nil || o.EnumStringRequired == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.EnumStringRequired
-}
-
-// GetEnumStringRequiredOk returns a tuple with the EnumStringRequired field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *EnumTest) GetEnumStringRequiredOk() (string, bool) {
-	if o == nil || o.EnumStringRequired == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.EnumStringRequired, true
-}
-
-// HasEnumStringRequired returns a boolean if a field has been set.
-func (o *EnumTest) HasEnumStringRequired() bool {
-	if o != nil && o.EnumStringRequired != nil {
-		return true
-	}
 
-	return false
+	return o.EnumStringRequired
 }
 
-// SetEnumStringRequired gets a reference to the given string and assigns it to the EnumStringRequired field.
+// SetEnumStringRequired sets field value
 func (o *EnumTest) SetEnumStringRequired(v string) {
-	o.EnumStringRequired = &v
+	o.EnumStringRequired = v
 }
 
-// GetEnumInteger returns the EnumInteger field if non-nil, zero value otherwise.
+// GetEnumInteger returns the EnumInteger field value if set, zero value otherwise.
 func (o *EnumTest) GetEnumInteger() int32 {
 	if o == nil || o.EnumInteger == nil {
 		var ret int32
@@ -101,7 +80,7 @@ func (o *EnumTest) GetEnumInteger() int32 {
 	return *o.EnumInteger
 }
 
-// GetEnumIntegerOk returns a tuple with the EnumInteger field if it's non-nil, zero value otherwise
+// GetEnumIntegerOk returns a tuple with the EnumInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *EnumTest) GetEnumIntegerOk() (int32, bool) {
 	if o == nil || o.EnumInteger == nil {
@@ -125,7 +104,7 @@ func (o *EnumTest) SetEnumInteger(v int32) {
 	o.EnumInteger = &v
 }
 
-// GetEnumNumber returns the EnumNumber field if non-nil, zero value otherwise.
+// GetEnumNumber returns the EnumNumber field value if set, zero value otherwise.
 func (o *EnumTest) GetEnumNumber() float64 {
 	if o == nil || o.EnumNumber == nil {
 		var ret float64
@@ -134,7 +113,7 @@ func (o *EnumTest) GetEnumNumber() float64 {
 	return *o.EnumNumber
 }
 
-// GetEnumNumberOk returns a tuple with the EnumNumber field if it's non-nil, zero value otherwise
+// GetEnumNumberOk returns a tuple with the EnumNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *EnumTest) GetEnumNumberOk() (float64, bool) {
 	if o == nil || o.EnumNumber == nil {
@@ -158,7 +137,7 @@ func (o *EnumTest) SetEnumNumber(v float64) {
 	o.EnumNumber = &v
 }
 
-// GetOuterEnum returns the OuterEnum field if non-nil, zero value otherwise.
+// GetOuterEnum returns the OuterEnum field value if set, zero value otherwise.
 func (o *EnumTest) GetOuterEnum() OuterEnum {
 	if o == nil || o.OuterEnum == nil {
 		var ret OuterEnum
@@ -167,7 +146,7 @@ func (o *EnumTest) GetOuterEnum() OuterEnum {
 	return *o.OuterEnum
 }
 
-// GetOuterEnumOk returns a tuple with the OuterEnum field if it's non-nil, zero value otherwise
+// GetOuterEnumOk returns a tuple with the OuterEnum field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *EnumTest) GetOuterEnumOk() (OuterEnum, bool) {
 	if o == nil || o.OuterEnum == nil {
@@ -191,29 +170,26 @@ func (o *EnumTest) SetOuterEnum(v OuterEnum) {
 	o.OuterEnum = &v
 }
 
+type NullableEnumTest struct {
+	Value EnumTest
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o EnumTest) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.EnumString != nil {
-		toSerialize["enum_string"] = o.EnumString
-	}
-	if o.EnumStringRequired == nil {
-		return nil, errors.New("EnumStringRequired is required and not nullable, but was not set on EnumTest")
-	}
-	if o.EnumStringRequired != nil {
-		toSerialize["enum_string_required"] = o.EnumStringRequired
-	}
-	if o.EnumInteger != nil {
-		toSerialize["enum_integer"] = o.EnumInteger
-	}
-	if o.EnumNumber != nil {
-		toSerialize["enum_number"] = o.EnumNumber
-	}
-	if o.OuterEnum != nil {
-		toSerialize["outerEnum"] = o.OuterEnum
-	}
-	return json.Marshal(toSerialize)
+func (v NullableEnumTest) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *NullableEnumTest) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_file.go b/samples/client/petstore/go-experimental/go-petstore/model_file.go
index 872952cc14ea..d35f12c08879 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_file.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_file.go
@@ -8,17 +8,19 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // File Must be named `File` for test.
 type File struct {
 	// Test capitalization
 	SourceURI *string `json:"sourceURI,omitempty"`
-
 }
 
-// GetSourceURI returns the SourceURI field if non-nil, zero value otherwise.
+// GetSourceURI returns the SourceURI field value if set, zero value otherwise.
 func (o *File) GetSourceURI() string {
 	if o == nil || o.SourceURI == nil {
 		var ret string
@@ -27,7 +29,7 @@ func (o *File) GetSourceURI() string {
 	return *o.SourceURI
 }
 
-// GetSourceURIOk returns a tuple with the SourceURI field if it's non-nil, zero value otherwise
+// GetSourceURIOk returns a tuple with the SourceURI field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *File) GetSourceURIOk() (string, bool) {
 	if o == nil || o.SourceURI == nil {
@@ -51,14 +53,26 @@ func (o *File) SetSourceURI(v string) {
 	o.SourceURI = &v
 }
 
+type NullableFile struct {
+	Value File
+	ExplicitNull bool
+}
+
+func (v NullableFile) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o File) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.SourceURI != nil {
-		toSerialize["sourceURI"] = o.SourceURI
+func (v *NullableFile) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_file_schema_test_class.go b/samples/client/petstore/go-experimental/go-petstore/model_file_schema_test_class.go
index 3926d06b2398..5c6a45436bea 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_file_schema_test_class.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_file_schema_test_class.go
@@ -8,18 +8,19 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // FileSchemaTestClass struct for FileSchemaTestClass
 type FileSchemaTestClass struct {
 	File *File `json:"file,omitempty"`
-
 	Files *[]File `json:"files,omitempty"`
-
 }
 
-// GetFile returns the File field if non-nil, zero value otherwise.
+// GetFile returns the File field value if set, zero value otherwise.
 func (o *FileSchemaTestClass) GetFile() File {
 	if o == nil || o.File == nil {
 		var ret File
@@ -28,7 +29,7 @@ func (o *FileSchemaTestClass) GetFile() File {
 	return *o.File
 }
 
-// GetFileOk returns a tuple with the File field if it's non-nil, zero value otherwise
+// GetFileOk returns a tuple with the File field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FileSchemaTestClass) GetFileOk() (File, bool) {
 	if o == nil || o.File == nil {
@@ -52,7 +53,7 @@ func (o *FileSchemaTestClass) SetFile(v File) {
 	o.File = &v
 }
 
-// GetFiles returns the Files field if non-nil, zero value otherwise.
+// GetFiles returns the Files field value if set, zero value otherwise.
 func (o *FileSchemaTestClass) GetFiles() []File {
 	if o == nil || o.Files == nil {
 		var ret []File
@@ -61,7 +62,7 @@ func (o *FileSchemaTestClass) GetFiles() []File {
 	return *o.Files
 }
 
-// GetFilesOk returns a tuple with the Files field if it's non-nil, zero value otherwise
+// GetFilesOk returns a tuple with the Files field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FileSchemaTestClass) GetFilesOk() ([]File, bool) {
 	if o == nil || o.Files == nil {
@@ -85,17 +86,26 @@ func (o *FileSchemaTestClass) SetFiles(v []File) {
 	o.Files = &v
 }
 
+type NullableFileSchemaTestClass struct {
+	Value FileSchemaTestClass
+	ExplicitNull bool
+}
+
+func (v NullableFileSchemaTestClass) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o FileSchemaTestClass) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.File != nil {
-		toSerialize["file"] = o.File
-	}
-	if o.Files != nil {
-		toSerialize["files"] = o.Files
+func (v *NullableFileSchemaTestClass) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_format_test_.go b/samples/client/petstore/go-experimental/go-petstore/model_format_test_.go
index c6de468fbfb4..6676cf826fbf 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_format_test_.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_format_test_.go
@@ -8,45 +8,33 @@
  */
 
 package petstore
+
 import (
+	"bytes"
+	"encoding/json"
 	"os"
 	"time"
-	"encoding/json"
-	"errors"
 )
+
 // FormatTest struct for FormatTest
 type FormatTest struct {
 	Integer *int32 `json:"integer,omitempty"`
-
 	Int32 *int32 `json:"int32,omitempty"`
-
 	Int64 *int64 `json:"int64,omitempty"`
-
-	Number *float32 `json:"number,omitempty"`
-
+	Number float32 `json:"number"`
 	Float *float32 `json:"float,omitempty"`
-
 	Double *float64 `json:"double,omitempty"`
-
 	String *string `json:"string,omitempty"`
-
-	Byte *string `json:"byte,omitempty"`
-
+	Byte string `json:"byte"`
 	Binary **os.File `json:"binary,omitempty"`
-
-	Date *string `json:"date,omitempty"`
-
+	Date string `json:"date"`
 	DateTime *time.Time `json:"dateTime,omitempty"`
-
 	Uuid *string `json:"uuid,omitempty"`
-
-	Password *string `json:"password,omitempty"`
-
+	Password string `json:"password"`
 	BigDecimal *float64 `json:"BigDecimal,omitempty"`
-
 }
 
-// GetInteger returns the Integer field if non-nil, zero value otherwise.
+// GetInteger returns the Integer field value if set, zero value otherwise.
 func (o *FormatTest) GetInteger() int32 {
 	if o == nil || o.Integer == nil {
 		var ret int32
@@ -55,7 +43,7 @@ func (o *FormatTest) GetInteger() int32 {
 	return *o.Integer
 }
 
-// GetIntegerOk returns a tuple with the Integer field if it's non-nil, zero value otherwise
+// GetIntegerOk returns a tuple with the Integer field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetIntegerOk() (int32, bool) {
 	if o == nil || o.Integer == nil {
@@ -79,7 +67,7 @@ func (o *FormatTest) SetInteger(v int32) {
 	o.Integer = &v
 }
 
-// GetInt32 returns the Int32 field if non-nil, zero value otherwise.
+// GetInt32 returns the Int32 field value if set, zero value otherwise.
 func (o *FormatTest) GetInt32() int32 {
 	if o == nil || o.Int32 == nil {
 		var ret int32
@@ -88,7 +76,7 @@ func (o *FormatTest) GetInt32() int32 {
 	return *o.Int32
 }
 
-// GetInt32Ok returns a tuple with the Int32 field if it's non-nil, zero value otherwise
+// GetInt32Ok returns a tuple with the Int32 field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetInt32Ok() (int32, bool) {
 	if o == nil || o.Int32 == nil {
@@ -112,7 +100,7 @@ func (o *FormatTest) SetInt32(v int32) {
 	o.Int32 = &v
 }
 
-// GetInt64 returns the Int64 field if non-nil, zero value otherwise.
+// GetInt64 returns the Int64 field value if set, zero value otherwise.
 func (o *FormatTest) GetInt64() int64 {
 	if o == nil || o.Int64 == nil {
 		var ret int64
@@ -121,7 +109,7 @@ func (o *FormatTest) GetInt64() int64 {
 	return *o.Int64
 }
 
-// GetInt64Ok returns a tuple with the Int64 field if it's non-nil, zero value otherwise
+// GetInt64Ok returns a tuple with the Int64 field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetInt64Ok() (int64, bool) {
 	if o == nil || o.Int64 == nil {
@@ -145,40 +133,22 @@ func (o *FormatTest) SetInt64(v int64) {
 	o.Int64 = &v
 }
 
-// GetNumber returns the Number field if non-nil, zero value otherwise.
+// GetNumber returns the Number field value
 func (o *FormatTest) GetNumber() float32 {
-	if o == nil || o.Number == nil {
+	if o == nil {
 		var ret float32
 		return ret
 	}
-	return *o.Number
-}
-
-// GetNumberOk returns a tuple with the Number field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *FormatTest) GetNumberOk() (float32, bool) {
-	if o == nil || o.Number == nil {
-		var ret float32
-		return ret, false
-	}
-	return *o.Number, true
-}
 
-// HasNumber returns a boolean if a field has been set.
-func (o *FormatTest) HasNumber() bool {
-	if o != nil && o.Number != nil {
-		return true
-	}
-
-	return false
+	return o.Number
 }
 
-// SetNumber gets a reference to the given float32 and assigns it to the Number field.
+// SetNumber sets field value
 func (o *FormatTest) SetNumber(v float32) {
-	o.Number = &v
+	o.Number = v
 }
 
-// GetFloat returns the Float field if non-nil, zero value otherwise.
+// GetFloat returns the Float field value if set, zero value otherwise.
 func (o *FormatTest) GetFloat() float32 {
 	if o == nil || o.Float == nil {
 		var ret float32
@@ -187,7 +157,7 @@ func (o *FormatTest) GetFloat() float32 {
 	return *o.Float
 }
 
-// GetFloatOk returns a tuple with the Float field if it's non-nil, zero value otherwise
+// GetFloatOk returns a tuple with the Float field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetFloatOk() (float32, bool) {
 	if o == nil || o.Float == nil {
@@ -211,7 +181,7 @@ func (o *FormatTest) SetFloat(v float32) {
 	o.Float = &v
 }
 
-// GetDouble returns the Double field if non-nil, zero value otherwise.
+// GetDouble returns the Double field value if set, zero value otherwise.
 func (o *FormatTest) GetDouble() float64 {
 	if o == nil || o.Double == nil {
 		var ret float64
@@ -220,7 +190,7 @@ func (o *FormatTest) GetDouble() float64 {
 	return *o.Double
 }
 
-// GetDoubleOk returns a tuple with the Double field if it's non-nil, zero value otherwise
+// GetDoubleOk returns a tuple with the Double field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetDoubleOk() (float64, bool) {
 	if o == nil || o.Double == nil {
@@ -244,7 +214,7 @@ func (o *FormatTest) SetDouble(v float64) {
 	o.Double = &v
 }
 
-// GetString returns the String field if non-nil, zero value otherwise.
+// GetString returns the String field value if set, zero value otherwise.
 func (o *FormatTest) GetString() string {
 	if o == nil || o.String == nil {
 		var ret string
@@ -253,7 +223,7 @@ func (o *FormatTest) GetString() string {
 	return *o.String
 }
 
-// GetStringOk returns a tuple with the String field if it's non-nil, zero value otherwise
+// GetStringOk returns a tuple with the String field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetStringOk() (string, bool) {
 	if o == nil || o.String == nil {
@@ -277,40 +247,22 @@ func (o *FormatTest) SetString(v string) {
 	o.String = &v
 }
 
-// GetByte returns the Byte field if non-nil, zero value otherwise.
+// GetByte returns the Byte field value
 func (o *FormatTest) GetByte() string {
-	if o == nil || o.Byte == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.Byte
-}
 
-// GetByteOk returns a tuple with the Byte field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *FormatTest) GetByteOk() (string, bool) {
-	if o == nil || o.Byte == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.Byte, true
-}
-
-// HasByte returns a boolean if a field has been set.
-func (o *FormatTest) HasByte() bool {
-	if o != nil && o.Byte != nil {
-		return true
-	}
-
-	return false
+	return o.Byte
 }
 
-// SetByte gets a reference to the given string and assigns it to the Byte field.
+// SetByte sets field value
 func (o *FormatTest) SetByte(v string) {
-	o.Byte = &v
+	o.Byte = v
 }
 
-// GetBinary returns the Binary field if non-nil, zero value otherwise.
+// GetBinary returns the Binary field value if set, zero value otherwise.
 func (o *FormatTest) GetBinary() *os.File {
 	if o == nil || o.Binary == nil {
 		var ret *os.File
@@ -319,7 +271,7 @@ func (o *FormatTest) GetBinary() *os.File {
 	return *o.Binary
 }
 
-// GetBinaryOk returns a tuple with the Binary field if it's non-nil, zero value otherwise
+// GetBinaryOk returns a tuple with the Binary field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetBinaryOk() (*os.File, bool) {
 	if o == nil || o.Binary == nil {
@@ -343,40 +295,22 @@ func (o *FormatTest) SetBinary(v *os.File) {
 	o.Binary = &v
 }
 
-// GetDate returns the Date field if non-nil, zero value otherwise.
+// GetDate returns the Date field value
 func (o *FormatTest) GetDate() string {
-	if o == nil || o.Date == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.Date
-}
-
-// GetDateOk returns a tuple with the Date field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *FormatTest) GetDateOk() (string, bool) {
-	if o == nil || o.Date == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.Date, true
-}
 
-// HasDate returns a boolean if a field has been set.
-func (o *FormatTest) HasDate() bool {
-	if o != nil && o.Date != nil {
-		return true
-	}
-
-	return false
+	return o.Date
 }
 
-// SetDate gets a reference to the given string and assigns it to the Date field.
+// SetDate sets field value
 func (o *FormatTest) SetDate(v string) {
-	o.Date = &v
+	o.Date = v
 }
 
-// GetDateTime returns the DateTime field if non-nil, zero value otherwise.
+// GetDateTime returns the DateTime field value if set, zero value otherwise.
 func (o *FormatTest) GetDateTime() time.Time {
 	if o == nil || o.DateTime == nil {
 		var ret time.Time
@@ -385,7 +319,7 @@ func (o *FormatTest) GetDateTime() time.Time {
 	return *o.DateTime
 }
 
-// GetDateTimeOk returns a tuple with the DateTime field if it's non-nil, zero value otherwise
+// GetDateTimeOk returns a tuple with the DateTime field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetDateTimeOk() (time.Time, bool) {
 	if o == nil || o.DateTime == nil {
@@ -409,7 +343,7 @@ func (o *FormatTest) SetDateTime(v time.Time) {
 	o.DateTime = &v
 }
 
-// GetUuid returns the Uuid field if non-nil, zero value otherwise.
+// GetUuid returns the Uuid field value if set, zero value otherwise.
 func (o *FormatTest) GetUuid() string {
 	if o == nil || o.Uuid == nil {
 		var ret string
@@ -418,7 +352,7 @@ func (o *FormatTest) GetUuid() string {
 	return *o.Uuid
 }
 
-// GetUuidOk returns a tuple with the Uuid field if it's non-nil, zero value otherwise
+// GetUuidOk returns a tuple with the Uuid field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetUuidOk() (string, bool) {
 	if o == nil || o.Uuid == nil {
@@ -442,40 +376,22 @@ func (o *FormatTest) SetUuid(v string) {
 	o.Uuid = &v
 }
 
-// GetPassword returns the Password field if non-nil, zero value otherwise.
+// GetPassword returns the Password field value
 func (o *FormatTest) GetPassword() string {
-	if o == nil || o.Password == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.Password
-}
 
-// GetPasswordOk returns a tuple with the Password field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *FormatTest) GetPasswordOk() (string, bool) {
-	if o == nil || o.Password == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.Password, true
-}
-
-// HasPassword returns a boolean if a field has been set.
-func (o *FormatTest) HasPassword() bool {
-	if o != nil && o.Password != nil {
-		return true
-	}
-
-	return false
+	return o.Password
 }
 
-// SetPassword gets a reference to the given string and assigns it to the Password field.
+// SetPassword sets field value
 func (o *FormatTest) SetPassword(v string) {
-	o.Password = &v
+	o.Password = v
 }
 
-// GetBigDecimal returns the BigDecimal field if non-nil, zero value otherwise.
+// GetBigDecimal returns the BigDecimal field value if set, zero value otherwise.
 func (o *FormatTest) GetBigDecimal() float64 {
 	if o == nil || o.BigDecimal == nil {
 		var ret float64
@@ -484,7 +400,7 @@ func (o *FormatTest) GetBigDecimal() float64 {
 	return *o.BigDecimal
 }
 
-// GetBigDecimalOk returns a tuple with the BigDecimal field if it's non-nil, zero value otherwise
+// GetBigDecimalOk returns a tuple with the BigDecimal field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *FormatTest) GetBigDecimalOk() (float64, bool) {
 	if o == nil || o.BigDecimal == nil {
@@ -508,65 +424,26 @@ func (o *FormatTest) SetBigDecimal(v float64) {
 	o.BigDecimal = &v
 }
 
+type NullableFormatTest struct {
+	Value FormatTest
+	ExplicitNull bool
+}
+
+func (v NullableFormatTest) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o FormatTest) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Integer != nil {
-		toSerialize["integer"] = o.Integer
-	}
-	if o.Int32 != nil {
-		toSerialize["int32"] = o.Int32
-	}
-	if o.Int64 != nil {
-		toSerialize["int64"] = o.Int64
-	}
-	if o.Number == nil {
-		return nil, errors.New("Number is required and not nullable, but was not set on FormatTest")
-	}
-	if o.Number != nil {
-		toSerialize["number"] = o.Number
-	}
-	if o.Float != nil {
-		toSerialize["float"] = o.Float
-	}
-	if o.Double != nil {
-		toSerialize["double"] = o.Double
-	}
-	if o.String != nil {
-		toSerialize["string"] = o.String
-	}
-	if o.Byte == nil {
-		return nil, errors.New("Byte is required and not nullable, but was not set on FormatTest")
-	}
-	if o.Byte != nil {
-		toSerialize["byte"] = o.Byte
+func (v *NullableFormatTest) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.Binary != nil {
-		toSerialize["binary"] = o.Binary
-	}
-	if o.Date == nil {
-		return nil, errors.New("Date is required and not nullable, but was not set on FormatTest")
-	}
-	if o.Date != nil {
-		toSerialize["date"] = o.Date
-	}
-	if o.DateTime != nil {
-		toSerialize["dateTime"] = o.DateTime
-	}
-	if o.Uuid != nil {
-		toSerialize["uuid"] = o.Uuid
-	}
-	if o.Password == nil {
-		return nil, errors.New("Password is required and not nullable, but was not set on FormatTest")
-	}
-	if o.Password != nil {
-		toSerialize["password"] = o.Password
-	}
-	if o.BigDecimal != nil {
-		toSerialize["BigDecimal"] = o.BigDecimal
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_has_only_read_only.go b/samples/client/petstore/go-experimental/go-petstore/model_has_only_read_only.go
index a36344fdf8ea..4d6a4ade3bab 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_has_only_read_only.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_has_only_read_only.go
@@ -8,18 +8,19 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // HasOnlyReadOnly struct for HasOnlyReadOnly
 type HasOnlyReadOnly struct {
 	Bar *string `json:"bar,omitempty"`
-
 	Foo *string `json:"foo,omitempty"`
-
 }
 
-// GetBar returns the Bar field if non-nil, zero value otherwise.
+// GetBar returns the Bar field value if set, zero value otherwise.
 func (o *HasOnlyReadOnly) GetBar() string {
 	if o == nil || o.Bar == nil {
 		var ret string
@@ -28,7 +29,7 @@ func (o *HasOnlyReadOnly) GetBar() string {
 	return *o.Bar
 }
 
-// GetBarOk returns a tuple with the Bar field if it's non-nil, zero value otherwise
+// GetBarOk returns a tuple with the Bar field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *HasOnlyReadOnly) GetBarOk() (string, bool) {
 	if o == nil || o.Bar == nil {
@@ -52,7 +53,7 @@ func (o *HasOnlyReadOnly) SetBar(v string) {
 	o.Bar = &v
 }
 
-// GetFoo returns the Foo field if non-nil, zero value otherwise.
+// GetFoo returns the Foo field value if set, zero value otherwise.
 func (o *HasOnlyReadOnly) GetFoo() string {
 	if o == nil || o.Foo == nil {
 		var ret string
@@ -61,7 +62,7 @@ func (o *HasOnlyReadOnly) GetFoo() string {
 	return *o.Foo
 }
 
-// GetFooOk returns a tuple with the Foo field if it's non-nil, zero value otherwise
+// GetFooOk returns a tuple with the Foo field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *HasOnlyReadOnly) GetFooOk() (string, bool) {
 	if o == nil || o.Foo == nil {
@@ -85,17 +86,26 @@ func (o *HasOnlyReadOnly) SetFoo(v string) {
 	o.Foo = &v
 }
 
+type NullableHasOnlyReadOnly struct {
+	Value HasOnlyReadOnly
+	ExplicitNull bool
+}
+
+func (v NullableHasOnlyReadOnly) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o HasOnlyReadOnly) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Bar != nil {
-		toSerialize["bar"] = o.Bar
-	}
-	if o.Foo != nil {
-		toSerialize["foo"] = o.Foo
+func (v *NullableHasOnlyReadOnly) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_list.go b/samples/client/petstore/go-experimental/go-petstore/model_list.go
index 2d1e013e6840..2e341b13fe21 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_list.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_list.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // List struct for List
 type List struct {
 	Var123List *string `json:"123-list,omitempty"`
-
 }
 
-// GetVar123List returns the Var123List field if non-nil, zero value otherwise.
+// GetVar123List returns the Var123List field value if set, zero value otherwise.
 func (o *List) GetVar123List() string {
 	if o == nil || o.Var123List == nil {
 		var ret string
@@ -26,7 +28,7 @@ func (o *List) GetVar123List() string {
 	return *o.Var123List
 }
 
-// GetVar123ListOk returns a tuple with the Var123List field if it's non-nil, zero value otherwise
+// GetVar123ListOk returns a tuple with the Var123List field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *List) GetVar123ListOk() (string, bool) {
 	if o == nil || o.Var123List == nil {
@@ -50,14 +52,26 @@ func (o *List) SetVar123List(v string) {
 	o.Var123List = &v
 }
 
+type NullableList struct {
+	Value List
+	ExplicitNull bool
+}
+
+func (v NullableList) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o List) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Var123List != nil {
-		toSerialize["123-list"] = o.Var123List
+func (v *NullableList) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_map_test_.go b/samples/client/petstore/go-experimental/go-petstore/model_map_test_.go
index 1f5db78738cc..482e2dcaa546 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_map_test_.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_map_test_.go
@@ -8,22 +8,21 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // MapTest struct for MapTest
 type MapTest struct {
 	MapMapOfString *map[string]map[string]string `json:"map_map_of_string,omitempty"`
-
 	MapOfEnumString *map[string]string `json:"map_of_enum_string,omitempty"`
-
 	DirectMap *map[string]bool `json:"direct_map,omitempty"`
-
 	IndirectMap *map[string]bool `json:"indirect_map,omitempty"`
-
 }
 
-// GetMapMapOfString returns the MapMapOfString field if non-nil, zero value otherwise.
+// GetMapMapOfString returns the MapMapOfString field value if set, zero value otherwise.
 func (o *MapTest) GetMapMapOfString() map[string]map[string]string {
 	if o == nil || o.MapMapOfString == nil {
 		var ret map[string]map[string]string
@@ -32,7 +31,7 @@ func (o *MapTest) GetMapMapOfString() map[string]map[string]string {
 	return *o.MapMapOfString
 }
 
-// GetMapMapOfStringOk returns a tuple with the MapMapOfString field if it's non-nil, zero value otherwise
+// GetMapMapOfStringOk returns a tuple with the MapMapOfString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *MapTest) GetMapMapOfStringOk() (map[string]map[string]string, bool) {
 	if o == nil || o.MapMapOfString == nil {
@@ -56,7 +55,7 @@ func (o *MapTest) SetMapMapOfString(v map[string]map[string]string) {
 	o.MapMapOfString = &v
 }
 
-// GetMapOfEnumString returns the MapOfEnumString field if non-nil, zero value otherwise.
+// GetMapOfEnumString returns the MapOfEnumString field value if set, zero value otherwise.
 func (o *MapTest) GetMapOfEnumString() map[string]string {
 	if o == nil || o.MapOfEnumString == nil {
 		var ret map[string]string
@@ -65,7 +64,7 @@ func (o *MapTest) GetMapOfEnumString() map[string]string {
 	return *o.MapOfEnumString
 }
 
-// GetMapOfEnumStringOk returns a tuple with the MapOfEnumString field if it's non-nil, zero value otherwise
+// GetMapOfEnumStringOk returns a tuple with the MapOfEnumString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *MapTest) GetMapOfEnumStringOk() (map[string]string, bool) {
 	if o == nil || o.MapOfEnumString == nil {
@@ -89,7 +88,7 @@ func (o *MapTest) SetMapOfEnumString(v map[string]string) {
 	o.MapOfEnumString = &v
 }
 
-// GetDirectMap returns the DirectMap field if non-nil, zero value otherwise.
+// GetDirectMap returns the DirectMap field value if set, zero value otherwise.
 func (o *MapTest) GetDirectMap() map[string]bool {
 	if o == nil || o.DirectMap == nil {
 		var ret map[string]bool
@@ -98,7 +97,7 @@ func (o *MapTest) GetDirectMap() map[string]bool {
 	return *o.DirectMap
 }
 
-// GetDirectMapOk returns a tuple with the DirectMap field if it's non-nil, zero value otherwise
+// GetDirectMapOk returns a tuple with the DirectMap field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *MapTest) GetDirectMapOk() (map[string]bool, bool) {
 	if o == nil || o.DirectMap == nil {
@@ -122,7 +121,7 @@ func (o *MapTest) SetDirectMap(v map[string]bool) {
 	o.DirectMap = &v
 }
 
-// GetIndirectMap returns the IndirectMap field if non-nil, zero value otherwise.
+// GetIndirectMap returns the IndirectMap field value if set, zero value otherwise.
 func (o *MapTest) GetIndirectMap() map[string]bool {
 	if o == nil || o.IndirectMap == nil {
 		var ret map[string]bool
@@ -131,7 +130,7 @@ func (o *MapTest) GetIndirectMap() map[string]bool {
 	return *o.IndirectMap
 }
 
-// GetIndirectMapOk returns a tuple with the IndirectMap field if it's non-nil, zero value otherwise
+// GetIndirectMapOk returns a tuple with the IndirectMap field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *MapTest) GetIndirectMapOk() (map[string]bool, bool) {
 	if o == nil || o.IndirectMap == nil {
@@ -155,23 +154,26 @@ func (o *MapTest) SetIndirectMap(v map[string]bool) {
 	o.IndirectMap = &v
 }
 
+type NullableMapTest struct {
+	Value MapTest
+	ExplicitNull bool
+}
+
+func (v NullableMapTest) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o MapTest) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.MapMapOfString != nil {
-		toSerialize["map_map_of_string"] = o.MapMapOfString
-	}
-	if o.MapOfEnumString != nil {
-		toSerialize["map_of_enum_string"] = o.MapOfEnumString
-	}
-	if o.DirectMap != nil {
-		toSerialize["direct_map"] = o.DirectMap
+func (v *NullableMapTest) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.IndirectMap != nil {
-		toSerialize["indirect_map"] = o.IndirectMap
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_mixed_properties_and_additional_properties_class.go b/samples/client/petstore/go-experimental/go-petstore/model_mixed_properties_and_additional_properties_class.go
index 8f8d81b2c586..29a15dd4b9bb 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_mixed_properties_and_additional_properties_class.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_mixed_properties_and_additional_properties_class.go
@@ -8,21 +8,21 @@
  */
 
 package petstore
+
 import (
-	"time"
+	"bytes"
 	"encoding/json"
+	"time"
 )
+
 // MixedPropertiesAndAdditionalPropertiesClass struct for MixedPropertiesAndAdditionalPropertiesClass
 type MixedPropertiesAndAdditionalPropertiesClass struct {
 	Uuid *string `json:"uuid,omitempty"`
-
 	DateTime *time.Time `json:"dateTime,omitempty"`
-
 	Map *map[string]Animal `json:"map,omitempty"`
-
 }
 
-// GetUuid returns the Uuid field if non-nil, zero value otherwise.
+// GetUuid returns the Uuid field value if set, zero value otherwise.
 func (o *MixedPropertiesAndAdditionalPropertiesClass) GetUuid() string {
 	if o == nil || o.Uuid == nil {
 		var ret string
@@ -31,7 +31,7 @@ func (o *MixedPropertiesAndAdditionalPropertiesClass) GetUuid() string {
 	return *o.Uuid
 }
 
-// GetUuidOk returns a tuple with the Uuid field if it's non-nil, zero value otherwise
+// GetUuidOk returns a tuple with the Uuid field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *MixedPropertiesAndAdditionalPropertiesClass) GetUuidOk() (string, bool) {
 	if o == nil || o.Uuid == nil {
@@ -55,7 +55,7 @@ func (o *MixedPropertiesAndAdditionalPropertiesClass) SetUuid(v string) {
 	o.Uuid = &v
 }
 
-// GetDateTime returns the DateTime field if non-nil, zero value otherwise.
+// GetDateTime returns the DateTime field value if set, zero value otherwise.
 func (o *MixedPropertiesAndAdditionalPropertiesClass) GetDateTime() time.Time {
 	if o == nil || o.DateTime == nil {
 		var ret time.Time
@@ -64,7 +64,7 @@ func (o *MixedPropertiesAndAdditionalPropertiesClass) GetDateTime() time.Time {
 	return *o.DateTime
 }
 
-// GetDateTimeOk returns a tuple with the DateTime field if it's non-nil, zero value otherwise
+// GetDateTimeOk returns a tuple with the DateTime field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *MixedPropertiesAndAdditionalPropertiesClass) GetDateTimeOk() (time.Time, bool) {
 	if o == nil || o.DateTime == nil {
@@ -88,7 +88,7 @@ func (o *MixedPropertiesAndAdditionalPropertiesClass) SetDateTime(v time.Time) {
 	o.DateTime = &v
 }
 
-// GetMap returns the Map field if non-nil, zero value otherwise.
+// GetMap returns the Map field value if set, zero value otherwise.
 func (o *MixedPropertiesAndAdditionalPropertiesClass) GetMap() map[string]Animal {
 	if o == nil || o.Map == nil {
 		var ret map[string]Animal
@@ -97,7 +97,7 @@ func (o *MixedPropertiesAndAdditionalPropertiesClass) GetMap() map[string]Animal
 	return *o.Map
 }
 
-// GetMapOk returns a tuple with the Map field if it's non-nil, zero value otherwise
+// GetMapOk returns a tuple with the Map field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *MixedPropertiesAndAdditionalPropertiesClass) GetMapOk() (map[string]Animal, bool) {
 	if o == nil || o.Map == nil {
@@ -121,20 +121,26 @@ func (o *MixedPropertiesAndAdditionalPropertiesClass) SetMap(v map[string]Animal
 	o.Map = &v
 }
 
+type NullableMixedPropertiesAndAdditionalPropertiesClass struct {
+	Value MixedPropertiesAndAdditionalPropertiesClass
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o MixedPropertiesAndAdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Uuid != nil {
-		toSerialize["uuid"] = o.Uuid
-	}
-	if o.DateTime != nil {
-		toSerialize["dateTime"] = o.DateTime
-	}
-	if o.Map != nil {
-		toSerialize["map"] = o.Map
-	}
-	return json.Marshal(toSerialize)
+func (v NullableMixedPropertiesAndAdditionalPropertiesClass) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *NullableMixedPropertiesAndAdditionalPropertiesClass) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_name.go b/samples/client/petstore/go-experimental/go-petstore/model_name.go
index ce720badba43..15cb31cf79f0 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_name.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_name.go
@@ -8,56 +8,36 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // Name Model for testing model name same as property name
 type Name struct {
-	Name *int32 `json:"name,omitempty"`
-
+	Name int32 `json:"name"`
 	SnakeCase *int32 `json:"snake_case,omitempty"`
-
 	Property *string `json:"property,omitempty"`
-
 	Var123Number *int32 `json:"123Number,omitempty"`
-
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value
 func (o *Name) GetName() int32 {
-	if o == nil || o.Name == nil {
+	if o == nil {
 		var ret int32
 		return ret
 	}
-	return *o.Name
-}
-
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *Name) GetNameOk() (int32, bool) {
-	if o == nil || o.Name == nil {
-		var ret int32
-		return ret, false
-	}
-	return *o.Name, true
-}
-
-// HasName returns a boolean if a field has been set.
-func (o *Name) HasName() bool {
-	if o != nil && o.Name != nil {
-		return true
-	}
 
-	return false
+	return o.Name
 }
 
-// SetName gets a reference to the given int32 and assigns it to the Name field.
+// SetName sets field value
 func (o *Name) SetName(v int32) {
-	o.Name = &v
+	o.Name = v
 }
 
-// GetSnakeCase returns the SnakeCase field if non-nil, zero value otherwise.
+// GetSnakeCase returns the SnakeCase field value if set, zero value otherwise.
 func (o *Name) GetSnakeCase() int32 {
 	if o == nil || o.SnakeCase == nil {
 		var ret int32
@@ -66,7 +46,7 @@ func (o *Name) GetSnakeCase() int32 {
 	return *o.SnakeCase
 }
 
-// GetSnakeCaseOk returns a tuple with the SnakeCase field if it's non-nil, zero value otherwise
+// GetSnakeCaseOk returns a tuple with the SnakeCase field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Name) GetSnakeCaseOk() (int32, bool) {
 	if o == nil || o.SnakeCase == nil {
@@ -90,7 +70,7 @@ func (o *Name) SetSnakeCase(v int32) {
 	o.SnakeCase = &v
 }
 
-// GetProperty returns the Property field if non-nil, zero value otherwise.
+// GetProperty returns the Property field value if set, zero value otherwise.
 func (o *Name) GetProperty() string {
 	if o == nil || o.Property == nil {
 		var ret string
@@ -99,7 +79,7 @@ func (o *Name) GetProperty() string {
 	return *o.Property
 }
 
-// GetPropertyOk returns a tuple with the Property field if it's non-nil, zero value otherwise
+// GetPropertyOk returns a tuple with the Property field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Name) GetPropertyOk() (string, bool) {
 	if o == nil || o.Property == nil {
@@ -123,7 +103,7 @@ func (o *Name) SetProperty(v string) {
 	o.Property = &v
 }
 
-// GetVar123Number returns the Var123Number field if non-nil, zero value otherwise.
+// GetVar123Number returns the Var123Number field value if set, zero value otherwise.
 func (o *Name) GetVar123Number() int32 {
 	if o == nil || o.Var123Number == nil {
 		var ret int32
@@ -132,7 +112,7 @@ func (o *Name) GetVar123Number() int32 {
 	return *o.Var123Number
 }
 
-// GetVar123NumberOk returns a tuple with the Var123Number field if it's non-nil, zero value otherwise
+// GetVar123NumberOk returns a tuple with the Var123Number field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Name) GetVar123NumberOk() (int32, bool) {
 	if o == nil || o.Var123Number == nil {
@@ -156,26 +136,26 @@ func (o *Name) SetVar123Number(v int32) {
 	o.Var123Number = &v
 }
 
+type NullableName struct {
+	Value Name
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Name) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Name == nil {
-		return nil, errors.New("Name is required and not nullable, but was not set on Name")
-	}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
-	}
-	if o.SnakeCase != nil {
-		toSerialize["snake_case"] = o.SnakeCase
-	}
-	if o.Property != nil {
-		toSerialize["property"] = o.Property
-	}
-	if o.Var123Number != nil {
-		toSerialize["123Number"] = o.Var123Number
-	}
-	return json.Marshal(toSerialize)
+func (v NullableName) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *NullableName) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_number_only.go b/samples/client/petstore/go-experimental/go-petstore/model_number_only.go
index 0cc88037cdd4..a844fb8128ab 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_number_only.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_number_only.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // NumberOnly struct for NumberOnly
 type NumberOnly struct {
 	JustNumber *float32 `json:"JustNumber,omitempty"`
-
 }
 
-// GetJustNumber returns the JustNumber field if non-nil, zero value otherwise.
+// GetJustNumber returns the JustNumber field value if set, zero value otherwise.
 func (o *NumberOnly) GetJustNumber() float32 {
 	if o == nil || o.JustNumber == nil {
 		var ret float32
@@ -26,7 +28,7 @@ func (o *NumberOnly) GetJustNumber() float32 {
 	return *o.JustNumber
 }
 
-// GetJustNumberOk returns a tuple with the JustNumber field if it's non-nil, zero value otherwise
+// GetJustNumberOk returns a tuple with the JustNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *NumberOnly) GetJustNumberOk() (float32, bool) {
 	if o == nil || o.JustNumber == nil {
@@ -50,14 +52,26 @@ func (o *NumberOnly) SetJustNumber(v float32) {
 	o.JustNumber = &v
 }
 
+type NullableNumberOnly struct {
+	Value NumberOnly
+	ExplicitNull bool
+}
+
+func (v NullableNumberOnly) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o NumberOnly) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.JustNumber != nil {
-		toSerialize["JustNumber"] = o.JustNumber
+func (v *NullableNumberOnly) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_order.go b/samples/client/petstore/go-experimental/go-petstore/model_order.go
index c0aefd904826..d138fa95cbae 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_order.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_order.go
@@ -8,28 +8,25 @@
  */
 
 package petstore
+
 import (
-	"time"
+	"bytes"
 	"encoding/json"
+	"time"
 )
+
 // Order struct for Order
 type Order struct {
 	Id *int64 `json:"id,omitempty"`
-
 	PetId *int64 `json:"petId,omitempty"`
-
 	Quantity *int32 `json:"quantity,omitempty"`
-
 	ShipDate *time.Time `json:"shipDate,omitempty"`
-
 	// Order Status
 	Status *string `json:"status,omitempty"`
-
 	Complete *bool `json:"complete,omitempty"`
-
 }
 
-// GetId returns the Id field if non-nil, zero value otherwise.
+// GetId returns the Id field value if set, zero value otherwise.
 func (o *Order) GetId() int64 {
 	if o == nil || o.Id == nil {
 		var ret int64
@@ -38,7 +35,7 @@ func (o *Order) GetId() int64 {
 	return *o.Id
 }
 
-// GetIdOk returns a tuple with the Id field if it's non-nil, zero value otherwise
+// GetIdOk returns a tuple with the Id field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Order) GetIdOk() (int64, bool) {
 	if o == nil || o.Id == nil {
@@ -62,7 +59,7 @@ func (o *Order) SetId(v int64) {
 	o.Id = &v
 }
 
-// GetPetId returns the PetId field if non-nil, zero value otherwise.
+// GetPetId returns the PetId field value if set, zero value otherwise.
 func (o *Order) GetPetId() int64 {
 	if o == nil || o.PetId == nil {
 		var ret int64
@@ -71,7 +68,7 @@ func (o *Order) GetPetId() int64 {
 	return *o.PetId
 }
 
-// GetPetIdOk returns a tuple with the PetId field if it's non-nil, zero value otherwise
+// GetPetIdOk returns a tuple with the PetId field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Order) GetPetIdOk() (int64, bool) {
 	if o == nil || o.PetId == nil {
@@ -95,7 +92,7 @@ func (o *Order) SetPetId(v int64) {
 	o.PetId = &v
 }
 
-// GetQuantity returns the Quantity field if non-nil, zero value otherwise.
+// GetQuantity returns the Quantity field value if set, zero value otherwise.
 func (o *Order) GetQuantity() int32 {
 	if o == nil || o.Quantity == nil {
 		var ret int32
@@ -104,7 +101,7 @@ func (o *Order) GetQuantity() int32 {
 	return *o.Quantity
 }
 
-// GetQuantityOk returns a tuple with the Quantity field if it's non-nil, zero value otherwise
+// GetQuantityOk returns a tuple with the Quantity field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Order) GetQuantityOk() (int32, bool) {
 	if o == nil || o.Quantity == nil {
@@ -128,7 +125,7 @@ func (o *Order) SetQuantity(v int32) {
 	o.Quantity = &v
 }
 
-// GetShipDate returns the ShipDate field if non-nil, zero value otherwise.
+// GetShipDate returns the ShipDate field value if set, zero value otherwise.
 func (o *Order) GetShipDate() time.Time {
 	if o == nil || o.ShipDate == nil {
 		var ret time.Time
@@ -137,7 +134,7 @@ func (o *Order) GetShipDate() time.Time {
 	return *o.ShipDate
 }
 
-// GetShipDateOk returns a tuple with the ShipDate field if it's non-nil, zero value otherwise
+// GetShipDateOk returns a tuple with the ShipDate field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Order) GetShipDateOk() (time.Time, bool) {
 	if o == nil || o.ShipDate == nil {
@@ -161,7 +158,7 @@ func (o *Order) SetShipDate(v time.Time) {
 	o.ShipDate = &v
 }
 
-// GetStatus returns the Status field if non-nil, zero value otherwise.
+// GetStatus returns the Status field value if set, zero value otherwise.
 func (o *Order) GetStatus() string {
 	if o == nil || o.Status == nil {
 		var ret string
@@ -170,7 +167,7 @@ func (o *Order) GetStatus() string {
 	return *o.Status
 }
 
-// GetStatusOk returns a tuple with the Status field if it's non-nil, zero value otherwise
+// GetStatusOk returns a tuple with the Status field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Order) GetStatusOk() (string, bool) {
 	if o == nil || o.Status == nil {
@@ -194,7 +191,7 @@ func (o *Order) SetStatus(v string) {
 	o.Status = &v
 }
 
-// GetComplete returns the Complete field if non-nil, zero value otherwise.
+// GetComplete returns the Complete field value if set, zero value otherwise.
 func (o *Order) GetComplete() bool {
 	if o == nil || o.Complete == nil {
 		var ret bool
@@ -203,7 +200,7 @@ func (o *Order) GetComplete() bool {
 	return *o.Complete
 }
 
-// GetCompleteOk returns a tuple with the Complete field if it's non-nil, zero value otherwise
+// GetCompleteOk returns a tuple with the Complete field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Order) GetCompleteOk() (bool, bool) {
 	if o == nil || o.Complete == nil {
@@ -227,29 +224,26 @@ func (o *Order) SetComplete(v bool) {
 	o.Complete = &v
 }
 
+type NullableOrder struct {
+	Value Order
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Order) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Id != nil {
-		toSerialize["id"] = o.Id
-	}
-	if o.PetId != nil {
-		toSerialize["petId"] = o.PetId
-	}
-	if o.Quantity != nil {
-		toSerialize["quantity"] = o.Quantity
-	}
-	if o.ShipDate != nil {
-		toSerialize["shipDate"] = o.ShipDate
-	}
-	if o.Status != nil {
-		toSerialize["status"] = o.Status
-	}
-	if o.Complete != nil {
-		toSerialize["complete"] = o.Complete
-	}
-	return json.Marshal(toSerialize)
+func (v NullableOrder) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *NullableOrder) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_outer_composite.go b/samples/client/petstore/go-experimental/go-petstore/model_outer_composite.go
index 1fe5d4103461..b22599eb6722 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_outer_composite.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_outer_composite.go
@@ -8,20 +8,20 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // OuterComposite struct for OuterComposite
 type OuterComposite struct {
 	MyNumber *float32 `json:"my_number,omitempty"`
-
 	MyString *string `json:"my_string,omitempty"`
-
 	MyBoolean *bool `json:"my_boolean,omitempty"`
-
 }
 
-// GetMyNumber returns the MyNumber field if non-nil, zero value otherwise.
+// GetMyNumber returns the MyNumber field value if set, zero value otherwise.
 func (o *OuterComposite) GetMyNumber() float32 {
 	if o == nil || o.MyNumber == nil {
 		var ret float32
@@ -30,7 +30,7 @@ func (o *OuterComposite) GetMyNumber() float32 {
 	return *o.MyNumber
 }
 
-// GetMyNumberOk returns a tuple with the MyNumber field if it's non-nil, zero value otherwise
+// GetMyNumberOk returns a tuple with the MyNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *OuterComposite) GetMyNumberOk() (float32, bool) {
 	if o == nil || o.MyNumber == nil {
@@ -54,7 +54,7 @@ func (o *OuterComposite) SetMyNumber(v float32) {
 	o.MyNumber = &v
 }
 
-// GetMyString returns the MyString field if non-nil, zero value otherwise.
+// GetMyString returns the MyString field value if set, zero value otherwise.
 func (o *OuterComposite) GetMyString() string {
 	if o == nil || o.MyString == nil {
 		var ret string
@@ -63,7 +63,7 @@ func (o *OuterComposite) GetMyString() string {
 	return *o.MyString
 }
 
-// GetMyStringOk returns a tuple with the MyString field if it's non-nil, zero value otherwise
+// GetMyStringOk returns a tuple with the MyString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *OuterComposite) GetMyStringOk() (string, bool) {
 	if o == nil || o.MyString == nil {
@@ -87,7 +87,7 @@ func (o *OuterComposite) SetMyString(v string) {
 	o.MyString = &v
 }
 
-// GetMyBoolean returns the MyBoolean field if non-nil, zero value otherwise.
+// GetMyBoolean returns the MyBoolean field value if set, zero value otherwise.
 func (o *OuterComposite) GetMyBoolean() bool {
 	if o == nil || o.MyBoolean == nil {
 		var ret bool
@@ -96,7 +96,7 @@ func (o *OuterComposite) GetMyBoolean() bool {
 	return *o.MyBoolean
 }
 
-// GetMyBooleanOk returns a tuple with the MyBoolean field if it's non-nil, zero value otherwise
+// GetMyBooleanOk returns a tuple with the MyBoolean field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *OuterComposite) GetMyBooleanOk() (bool, bool) {
 	if o == nil || o.MyBoolean == nil {
@@ -120,20 +120,26 @@ func (o *OuterComposite) SetMyBoolean(v bool) {
 	o.MyBoolean = &v
 }
 
+type NullableOuterComposite struct {
+	Value OuterComposite
+	ExplicitNull bool
+}
+
+func (v NullableOuterComposite) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o OuterComposite) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.MyNumber != nil {
-		toSerialize["my_number"] = o.MyNumber
-	}
-	if o.MyString != nil {
-		toSerialize["my_string"] = o.MyString
+func (v *NullableOuterComposite) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.MyBoolean != nil {
-		toSerialize["my_boolean"] = o.MyBoolean
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_outer_enum.go b/samples/client/petstore/go-experimental/go-petstore/model_outer_enum.go
index f133b6fc890c..b6385fcb5630 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_outer_enum.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_outer_enum.go
@@ -8,6 +8,12 @@
  */
 
 package petstore
+
+import (
+	"bytes"
+	"encoding/json"
+)
+
 // OuterEnum the model 'OuterEnum'
 type OuterEnum string
 
@@ -18,4 +24,30 @@ const (
 	DELIVERED OuterEnum = "delivered"
 )
 
+type NullableOuterEnum struct {
+	Value OuterEnum
+	ExplicitNull bool
+}
+
+func (v NullableOuterEnum) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != "":
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
+
+func (v *NullableOuterEnum) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
+
+
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_pet.go b/samples/client/petstore/go-experimental/go-petstore/model_pet.go
index 110a21e094e4..405a179218b7 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_pet.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_pet.go
@@ -8,28 +8,24 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // Pet struct for Pet
 type Pet struct {
 	Id *int64 `json:"id,omitempty"`
-
 	Category *Category `json:"category,omitempty"`
-
-	Name *string `json:"name,omitempty"`
-
-	PhotoUrls *[]string `json:"photoUrls,omitempty"`
-
+	Name string `json:"name"`
+	PhotoUrls []string `json:"photoUrls"`
 	Tags *[]Tag `json:"tags,omitempty"`
-
 	// pet status in the store
 	Status *string `json:"status,omitempty"`
-
 }
 
-// GetId returns the Id field if non-nil, zero value otherwise.
+// GetId returns the Id field value if set, zero value otherwise.
 func (o *Pet) GetId() int64 {
 	if o == nil || o.Id == nil {
 		var ret int64
@@ -38,7 +34,7 @@ func (o *Pet) GetId() int64 {
 	return *o.Id
 }
 
-// GetIdOk returns a tuple with the Id field if it's non-nil, zero value otherwise
+// GetIdOk returns a tuple with the Id field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Pet) GetIdOk() (int64, bool) {
 	if o == nil || o.Id == nil {
@@ -62,7 +58,7 @@ func (o *Pet) SetId(v int64) {
 	o.Id = &v
 }
 
-// GetCategory returns the Category field if non-nil, zero value otherwise.
+// GetCategory returns the Category field value if set, zero value otherwise.
 func (o *Pet) GetCategory() Category {
 	if o == nil || o.Category == nil {
 		var ret Category
@@ -71,7 +67,7 @@ func (o *Pet) GetCategory() Category {
 	return *o.Category
 }
 
-// GetCategoryOk returns a tuple with the Category field if it's non-nil, zero value otherwise
+// GetCategoryOk returns a tuple with the Category field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Pet) GetCategoryOk() (Category, bool) {
 	if o == nil || o.Category == nil {
@@ -95,73 +91,37 @@ func (o *Pet) SetCategory(v Category) {
 	o.Category = &v
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value
 func (o *Pet) GetName() string {
-	if o == nil || o.Name == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.Name
-}
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *Pet) GetNameOk() (string, bool) {
-	if o == nil || o.Name == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.Name, true
-}
-
-// HasName returns a boolean if a field has been set.
-func (o *Pet) HasName() bool {
-	if o != nil && o.Name != nil {
-		return true
-	}
-
-	return false
+	return o.Name
 }
 
-// SetName gets a reference to the given string and assigns it to the Name field.
+// SetName sets field value
 func (o *Pet) SetName(v string) {
-	o.Name = &v
+	o.Name = v
 }
 
-// GetPhotoUrls returns the PhotoUrls field if non-nil, zero value otherwise.
+// GetPhotoUrls returns the PhotoUrls field value
 func (o *Pet) GetPhotoUrls() []string {
-	if o == nil || o.PhotoUrls == nil {
+	if o == nil {
 		var ret []string
 		return ret
 	}
-	return *o.PhotoUrls
-}
-
-// GetPhotoUrlsOk returns a tuple with the PhotoUrls field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *Pet) GetPhotoUrlsOk() ([]string, bool) {
-	if o == nil || o.PhotoUrls == nil {
-		var ret []string
-		return ret, false
-	}
-	return *o.PhotoUrls, true
-}
 
-// HasPhotoUrls returns a boolean if a field has been set.
-func (o *Pet) HasPhotoUrls() bool {
-	if o != nil && o.PhotoUrls != nil {
-		return true
-	}
-
-	return false
+	return o.PhotoUrls
 }
 
-// SetPhotoUrls gets a reference to the given []string and assigns it to the PhotoUrls field.
+// SetPhotoUrls sets field value
 func (o *Pet) SetPhotoUrls(v []string) {
-	o.PhotoUrls = &v
+	o.PhotoUrls = v
 }
 
-// GetTags returns the Tags field if non-nil, zero value otherwise.
+// GetTags returns the Tags field value if set, zero value otherwise.
 func (o *Pet) GetTags() []Tag {
 	if o == nil || o.Tags == nil {
 		var ret []Tag
@@ -170,7 +130,7 @@ func (o *Pet) GetTags() []Tag {
 	return *o.Tags
 }
 
-// GetTagsOk returns a tuple with the Tags field if it's non-nil, zero value otherwise
+// GetTagsOk returns a tuple with the Tags field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Pet) GetTagsOk() ([]Tag, bool) {
 	if o == nil || o.Tags == nil {
@@ -194,7 +154,7 @@ func (o *Pet) SetTags(v []Tag) {
 	o.Tags = &v
 }
 
-// GetStatus returns the Status field if non-nil, zero value otherwise.
+// GetStatus returns the Status field value if set, zero value otherwise.
 func (o *Pet) GetStatus() string {
 	if o == nil || o.Status == nil {
 		var ret string
@@ -203,7 +163,7 @@ func (o *Pet) GetStatus() string {
 	return *o.Status
 }
 
-// GetStatusOk returns a tuple with the Status field if it's non-nil, zero value otherwise
+// GetStatusOk returns a tuple with the Status field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Pet) GetStatusOk() (string, bool) {
 	if o == nil || o.Status == nil {
@@ -227,35 +187,26 @@ func (o *Pet) SetStatus(v string) {
 	o.Status = &v
 }
 
+type NullablePet struct {
+	Value Pet
+	ExplicitNull bool
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Pet) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Id != nil {
-		toSerialize["id"] = o.Id
-	}
-	if o.Category != nil {
-		toSerialize["category"] = o.Category
-	}
-	if o.Name == nil {
-		return nil, errors.New("Name is required and not nullable, but was not set on Pet")
-	}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
-	}
-	if o.PhotoUrls == nil {
-		return nil, errors.New("PhotoUrls is required and not nullable, but was not set on Pet")
-	}
-	if o.PhotoUrls != nil {
-		toSerialize["photoUrls"] = o.PhotoUrls
-	}
-	if o.Tags != nil {
-		toSerialize["tags"] = o.Tags
-	}
-	if o.Status != nil {
-		toSerialize["status"] = o.Status
-	}
-	return json.Marshal(toSerialize)
+func (v NullablePet) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
 }
 
+func (v *NullablePet) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
+	}
+
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_read_only_first.go b/samples/client/petstore/go-experimental/go-petstore/model_read_only_first.go
index 4ed8a2571764..bdd9807ca899 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_read_only_first.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_read_only_first.go
@@ -8,18 +8,19 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // ReadOnlyFirst struct for ReadOnlyFirst
 type ReadOnlyFirst struct {
 	Bar *string `json:"bar,omitempty"`
-
 	Baz *string `json:"baz,omitempty"`
-
 }
 
-// GetBar returns the Bar field if non-nil, zero value otherwise.
+// GetBar returns the Bar field value if set, zero value otherwise.
 func (o *ReadOnlyFirst) GetBar() string {
 	if o == nil || o.Bar == nil {
 		var ret string
@@ -28,7 +29,7 @@ func (o *ReadOnlyFirst) GetBar() string {
 	return *o.Bar
 }
 
-// GetBarOk returns a tuple with the Bar field if it's non-nil, zero value otherwise
+// GetBarOk returns a tuple with the Bar field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ReadOnlyFirst) GetBarOk() (string, bool) {
 	if o == nil || o.Bar == nil {
@@ -52,7 +53,7 @@ func (o *ReadOnlyFirst) SetBar(v string) {
 	o.Bar = &v
 }
 
-// GetBaz returns the Baz field if non-nil, zero value otherwise.
+// GetBaz returns the Baz field value if set, zero value otherwise.
 func (o *ReadOnlyFirst) GetBaz() string {
 	if o == nil || o.Baz == nil {
 		var ret string
@@ -61,7 +62,7 @@ func (o *ReadOnlyFirst) GetBaz() string {
 	return *o.Baz
 }
 
-// GetBazOk returns a tuple with the Baz field if it's non-nil, zero value otherwise
+// GetBazOk returns a tuple with the Baz field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *ReadOnlyFirst) GetBazOk() (string, bool) {
 	if o == nil || o.Baz == nil {
@@ -85,17 +86,26 @@ func (o *ReadOnlyFirst) SetBaz(v string) {
 	o.Baz = &v
 }
 
+type NullableReadOnlyFirst struct {
+	Value ReadOnlyFirst
+	ExplicitNull bool
+}
+
+func (v NullableReadOnlyFirst) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o ReadOnlyFirst) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Bar != nil {
-		toSerialize["bar"] = o.Bar
-	}
-	if o.Baz != nil {
-		toSerialize["baz"] = o.Baz
+func (v *NullableReadOnlyFirst) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_return.go b/samples/client/petstore/go-experimental/go-petstore/model_return.go
index c694495fdac8..14821a5ca747 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_return.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_return.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // Return Model for testing reserved words
 type Return struct {
 	Return *int32 `json:"return,omitempty"`
-
 }
 
-// GetReturn returns the Return field if non-nil, zero value otherwise.
+// GetReturn returns the Return field value if set, zero value otherwise.
 func (o *Return) GetReturn() int32 {
 	if o == nil || o.Return == nil {
 		var ret int32
@@ -26,7 +28,7 @@ func (o *Return) GetReturn() int32 {
 	return *o.Return
 }
 
-// GetReturnOk returns a tuple with the Return field if it's non-nil, zero value otherwise
+// GetReturnOk returns a tuple with the Return field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Return) GetReturnOk() (int32, bool) {
 	if o == nil || o.Return == nil {
@@ -50,14 +52,26 @@ func (o *Return) SetReturn(v int32) {
 	o.Return = &v
 }
 
+type NullableReturn struct {
+	Value Return
+	ExplicitNull bool
+}
+
+func (v NullableReturn) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Return) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Return != nil {
-		toSerialize["return"] = o.Return
+func (v *NullableReturn) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_special_model_name.go b/samples/client/petstore/go-experimental/go-petstore/model_special_model_name.go
index 5568361e1d5f..abafacb4e4dd 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_special_model_name.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_special_model_name.go
@@ -8,16 +8,18 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // SpecialModelName struct for SpecialModelName
 type SpecialModelName struct {
 	SpecialPropertyName *int64 `json:"$special[property.name],omitempty"`
-
 }
 
-// GetSpecialPropertyName returns the SpecialPropertyName field if non-nil, zero value otherwise.
+// GetSpecialPropertyName returns the SpecialPropertyName field value if set, zero value otherwise.
 func (o *SpecialModelName) GetSpecialPropertyName() int64 {
 	if o == nil || o.SpecialPropertyName == nil {
 		var ret int64
@@ -26,7 +28,7 @@ func (o *SpecialModelName) GetSpecialPropertyName() int64 {
 	return *o.SpecialPropertyName
 }
 
-// GetSpecialPropertyNameOk returns a tuple with the SpecialPropertyName field if it's non-nil, zero value otherwise
+// GetSpecialPropertyNameOk returns a tuple with the SpecialPropertyName field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *SpecialModelName) GetSpecialPropertyNameOk() (int64, bool) {
 	if o == nil || o.SpecialPropertyName == nil {
@@ -50,14 +52,26 @@ func (o *SpecialModelName) SetSpecialPropertyName(v int64) {
 	o.SpecialPropertyName = &v
 }
 
+type NullableSpecialModelName struct {
+	Value SpecialModelName
+	ExplicitNull bool
+}
+
+func (v NullableSpecialModelName) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o SpecialModelName) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.SpecialPropertyName != nil {
-		toSerialize["$special[property.name]"] = o.SpecialPropertyName
+func (v *NullableSpecialModelName) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_tag.go b/samples/client/petstore/go-experimental/go-petstore/model_tag.go
index 063283820e92..a702f37f0939 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_tag.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_tag.go
@@ -8,18 +8,19 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // Tag struct for Tag
 type Tag struct {
 	Id *int64 `json:"id,omitempty"`
-
 	Name *string `json:"name,omitempty"`
-
 }
 
-// GetId returns the Id field if non-nil, zero value otherwise.
+// GetId returns the Id field value if set, zero value otherwise.
 func (o *Tag) GetId() int64 {
 	if o == nil || o.Id == nil {
 		var ret int64
@@ -28,7 +29,7 @@ func (o *Tag) GetId() int64 {
 	return *o.Id
 }
 
-// GetIdOk returns a tuple with the Id field if it's non-nil, zero value otherwise
+// GetIdOk returns a tuple with the Id field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Tag) GetIdOk() (int64, bool) {
 	if o == nil || o.Id == nil {
@@ -52,7 +53,7 @@ func (o *Tag) SetId(v int64) {
 	o.Id = &v
 }
 
-// GetName returns the Name field if non-nil, zero value otherwise.
+// GetName returns the Name field value if set, zero value otherwise.
 func (o *Tag) GetName() string {
 	if o == nil || o.Name == nil {
 		var ret string
@@ -61,7 +62,7 @@ func (o *Tag) GetName() string {
 	return *o.Name
 }
 
-// GetNameOk returns a tuple with the Name field if it's non-nil, zero value otherwise
+// GetNameOk returns a tuple with the Name field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *Tag) GetNameOk() (string, bool) {
 	if o == nil || o.Name == nil {
@@ -85,17 +86,26 @@ func (o *Tag) SetName(v string) {
 	o.Name = &v
 }
 
+type NullableTag struct {
+	Value Tag
+	ExplicitNull bool
+}
+
+func (v NullableTag) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o Tag) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Id != nil {
-		toSerialize["id"] = o.Id
-	}
-	if o.Name != nil {
-		toSerialize["name"] = o.Name
+func (v *NullableTag) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_type_holder_default.go b/samples/client/petstore/go-experimental/go-petstore/model_type_holder_default.go
index 7022b082547d..173bd1c1b98e 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_type_holder_default.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_type_holder_default.go
@@ -8,224 +8,116 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // TypeHolderDefault struct for TypeHolderDefault
 type TypeHolderDefault struct {
-	StringItem *string `json:"string_item,omitempty"`
-
-	NumberItem *float32 `json:"number_item,omitempty"`
-
-	IntegerItem *int32 `json:"integer_item,omitempty"`
-
-	BoolItem *bool `json:"bool_item,omitempty"`
-
-	ArrayItem *[]int32 `json:"array_item,omitempty"`
-
+	StringItem string `json:"string_item"`
+	NumberItem float32 `json:"number_item"`
+	IntegerItem int32 `json:"integer_item"`
+	BoolItem bool `json:"bool_item"`
+	ArrayItem []int32 `json:"array_item"`
 }
 
-// GetStringItem returns the StringItem field if non-nil, zero value otherwise.
+// GetStringItem returns the StringItem field value
 func (o *TypeHolderDefault) GetStringItem() string {
-	if o == nil || o.StringItem == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.StringItem
-}
-
-// GetStringItemOk returns a tuple with the StringItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderDefault) GetStringItemOk() (string, bool) {
-	if o == nil || o.StringItem == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.StringItem, true
-}
-
-// HasStringItem returns a boolean if a field has been set.
-func (o *TypeHolderDefault) HasStringItem() bool {
-	if o != nil && o.StringItem != nil {
-		return true
-	}
 
-	return false
+	return o.StringItem
 }
 
-// SetStringItem gets a reference to the given string and assigns it to the StringItem field.
+// SetStringItem sets field value
 func (o *TypeHolderDefault) SetStringItem(v string) {
-	o.StringItem = &v
+	o.StringItem = v
 }
 
-// GetNumberItem returns the NumberItem field if non-nil, zero value otherwise.
+// GetNumberItem returns the NumberItem field value
 func (o *TypeHolderDefault) GetNumberItem() float32 {
-	if o == nil || o.NumberItem == nil {
+	if o == nil {
 		var ret float32
 		return ret
 	}
-	return *o.NumberItem
-}
-
-// GetNumberItemOk returns a tuple with the NumberItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderDefault) GetNumberItemOk() (float32, bool) {
-	if o == nil || o.NumberItem == nil {
-		var ret float32
-		return ret, false
-	}
-	return *o.NumberItem, true
-}
-
-// HasNumberItem returns a boolean if a field has been set.
-func (o *TypeHolderDefault) HasNumberItem() bool {
-	if o != nil && o.NumberItem != nil {
-		return true
-	}
 
-	return false
+	return o.NumberItem
 }
 
-// SetNumberItem gets a reference to the given float32 and assigns it to the NumberItem field.
+// SetNumberItem sets field value
 func (o *TypeHolderDefault) SetNumberItem(v float32) {
-	o.NumberItem = &v
+	o.NumberItem = v
 }
 
-// GetIntegerItem returns the IntegerItem field if non-nil, zero value otherwise.
+// GetIntegerItem returns the IntegerItem field value
 func (o *TypeHolderDefault) GetIntegerItem() int32 {
-	if o == nil || o.IntegerItem == nil {
+	if o == nil {
 		var ret int32
 		return ret
 	}
-	return *o.IntegerItem
-}
-
-// GetIntegerItemOk returns a tuple with the IntegerItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderDefault) GetIntegerItemOk() (int32, bool) {
-	if o == nil || o.IntegerItem == nil {
-		var ret int32
-		return ret, false
-	}
-	return *o.IntegerItem, true
-}
-
-// HasIntegerItem returns a boolean if a field has been set.
-func (o *TypeHolderDefault) HasIntegerItem() bool {
-	if o != nil && o.IntegerItem != nil {
-		return true
-	}
 
-	return false
+	return o.IntegerItem
 }
 
-// SetIntegerItem gets a reference to the given int32 and assigns it to the IntegerItem field.
+// SetIntegerItem sets field value
 func (o *TypeHolderDefault) SetIntegerItem(v int32) {
-	o.IntegerItem = &v
+	o.IntegerItem = v
 }
 
-// GetBoolItem returns the BoolItem field if non-nil, zero value otherwise.
+// GetBoolItem returns the BoolItem field value
 func (o *TypeHolderDefault) GetBoolItem() bool {
-	if o == nil || o.BoolItem == nil {
+	if o == nil {
 		var ret bool
 		return ret
 	}
-	return *o.BoolItem
-}
-
-// GetBoolItemOk returns a tuple with the BoolItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderDefault) GetBoolItemOk() (bool, bool) {
-	if o == nil || o.BoolItem == nil {
-		var ret bool
-		return ret, false
-	}
-	return *o.BoolItem, true
-}
-
-// HasBoolItem returns a boolean if a field has been set.
-func (o *TypeHolderDefault) HasBoolItem() bool {
-	if o != nil && o.BoolItem != nil {
-		return true
-	}
 
-	return false
+	return o.BoolItem
 }
 
-// SetBoolItem gets a reference to the given bool and assigns it to the BoolItem field.
+// SetBoolItem sets field value
 func (o *TypeHolderDefault) SetBoolItem(v bool) {
-	o.BoolItem = &v
+	o.BoolItem = v
 }
 
-// GetArrayItem returns the ArrayItem field if non-nil, zero value otherwise.
+// GetArrayItem returns the ArrayItem field value
 func (o *TypeHolderDefault) GetArrayItem() []int32 {
-	if o == nil || o.ArrayItem == nil {
+	if o == nil {
 		var ret []int32
 		return ret
 	}
-	return *o.ArrayItem
-}
 
-// GetArrayItemOk returns a tuple with the ArrayItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderDefault) GetArrayItemOk() ([]int32, bool) {
-	if o == nil || o.ArrayItem == nil {
-		var ret []int32
-		return ret, false
-	}
-	return *o.ArrayItem, true
+	return o.ArrayItem
 }
 
-// HasArrayItem returns a boolean if a field has been set.
-func (o *TypeHolderDefault) HasArrayItem() bool {
-	if o != nil && o.ArrayItem != nil {
-		return true
-	}
-
-	return false
+// SetArrayItem sets field value
+func (o *TypeHolderDefault) SetArrayItem(v []int32) {
+	o.ArrayItem = v
 }
 
-// SetArrayItem gets a reference to the given []int32 and assigns it to the ArrayItem field.
-func (o *TypeHolderDefault) SetArrayItem(v []int32) {
-	o.ArrayItem = &v
+type NullableTypeHolderDefault struct {
+	Value TypeHolderDefault
+	ExplicitNull bool
 }
 
+func (v NullableTypeHolderDefault) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o TypeHolderDefault) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.StringItem == nil {
-		return nil, errors.New("StringItem is required and not nullable, but was not set on TypeHolderDefault")
-	}
-	if o.StringItem != nil {
-		toSerialize["string_item"] = o.StringItem
-	}
-	if o.NumberItem == nil {
-		return nil, errors.New("NumberItem is required and not nullable, but was not set on TypeHolderDefault")
-	}
-	if o.NumberItem != nil {
-		toSerialize["number_item"] = o.NumberItem
-	}
-	if o.IntegerItem == nil {
-		return nil, errors.New("IntegerItem is required and not nullable, but was not set on TypeHolderDefault")
-	}
-	if o.IntegerItem != nil {
-		toSerialize["integer_item"] = o.IntegerItem
+func (v *NullableTypeHolderDefault) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.BoolItem == nil {
-		return nil, errors.New("BoolItem is required and not nullable, but was not set on TypeHolderDefault")
-	}
-	if o.BoolItem != nil {
-		toSerialize["bool_item"] = o.BoolItem
-	}
-	if o.ArrayItem == nil {
-		return nil, errors.New("ArrayItem is required and not nullable, but was not set on TypeHolderDefault")
-	}
-	if o.ArrayItem != nil {
-		toSerialize["array_item"] = o.ArrayItem
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_type_holder_example.go b/samples/client/petstore/go-experimental/go-petstore/model_type_holder_example.go
index e51025fcb74b..6cd9a0867caf 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_type_holder_example.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_type_holder_example.go
@@ -8,265 +8,132 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
-	"errors"
 )
+
 // TypeHolderExample struct for TypeHolderExample
 type TypeHolderExample struct {
-	StringItem *string `json:"string_item,omitempty"`
-
-	NumberItem *float32 `json:"number_item,omitempty"`
-
-	FloatItem *float32 `json:"float_item,omitempty"`
-
-	IntegerItem *int32 `json:"integer_item,omitempty"`
-
-	BoolItem *bool `json:"bool_item,omitempty"`
-
-	ArrayItem *[]int32 `json:"array_item,omitempty"`
-
+	StringItem string `json:"string_item"`
+	NumberItem float32 `json:"number_item"`
+	FloatItem float32 `json:"float_item"`
+	IntegerItem int32 `json:"integer_item"`
+	BoolItem bool `json:"bool_item"`
+	ArrayItem []int32 `json:"array_item"`
 }
 
-// GetStringItem returns the StringItem field if non-nil, zero value otherwise.
+// GetStringItem returns the StringItem field value
 func (o *TypeHolderExample) GetStringItem() string {
-	if o == nil || o.StringItem == nil {
+	if o == nil {
 		var ret string
 		return ret
 	}
-	return *o.StringItem
-}
-
-// GetStringItemOk returns a tuple with the StringItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderExample) GetStringItemOk() (string, bool) {
-	if o == nil || o.StringItem == nil {
-		var ret string
-		return ret, false
-	}
-	return *o.StringItem, true
-}
-
-// HasStringItem returns a boolean if a field has been set.
-func (o *TypeHolderExample) HasStringItem() bool {
-	if o != nil && o.StringItem != nil {
-		return true
-	}
 
-	return false
+	return o.StringItem
 }
 
-// SetStringItem gets a reference to the given string and assigns it to the StringItem field.
+// SetStringItem sets field value
 func (o *TypeHolderExample) SetStringItem(v string) {
-	o.StringItem = &v
+	o.StringItem = v
 }
 
-// GetNumberItem returns the NumberItem field if non-nil, zero value otherwise.
+// GetNumberItem returns the NumberItem field value
 func (o *TypeHolderExample) GetNumberItem() float32 {
-	if o == nil || o.NumberItem == nil {
+	if o == nil {
 		var ret float32
 		return ret
 	}
-	return *o.NumberItem
-}
-
-// GetNumberItemOk returns a tuple with the NumberItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderExample) GetNumberItemOk() (float32, bool) {
-	if o == nil || o.NumberItem == nil {
-		var ret float32
-		return ret, false
-	}
-	return *o.NumberItem, true
-}
-
-// HasNumberItem returns a boolean if a field has been set.
-func (o *TypeHolderExample) HasNumberItem() bool {
-	if o != nil && o.NumberItem != nil {
-		return true
-	}
 
-	return false
+	return o.NumberItem
 }
 
-// SetNumberItem gets a reference to the given float32 and assigns it to the NumberItem field.
+// SetNumberItem sets field value
 func (o *TypeHolderExample) SetNumberItem(v float32) {
-	o.NumberItem = &v
+	o.NumberItem = v
 }
 
-// GetFloatItem returns the FloatItem field if non-nil, zero value otherwise.
+// GetFloatItem returns the FloatItem field value
 func (o *TypeHolderExample) GetFloatItem() float32 {
-	if o == nil || o.FloatItem == nil {
+	if o == nil {
 		var ret float32
 		return ret
 	}
-	return *o.FloatItem
-}
-
-// GetFloatItemOk returns a tuple with the FloatItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderExample) GetFloatItemOk() (float32, bool) {
-	if o == nil || o.FloatItem == nil {
-		var ret float32
-		return ret, false
-	}
-	return *o.FloatItem, true
-}
-
-// HasFloatItem returns a boolean if a field has been set.
-func (o *TypeHolderExample) HasFloatItem() bool {
-	if o != nil && o.FloatItem != nil {
-		return true
-	}
 
-	return false
+	return o.FloatItem
 }
 
-// SetFloatItem gets a reference to the given float32 and assigns it to the FloatItem field.
+// SetFloatItem sets field value
 func (o *TypeHolderExample) SetFloatItem(v float32) {
-	o.FloatItem = &v
+	o.FloatItem = v
 }
 
-// GetIntegerItem returns the IntegerItem field if non-nil, zero value otherwise.
+// GetIntegerItem returns the IntegerItem field value
 func (o *TypeHolderExample) GetIntegerItem() int32 {
-	if o == nil || o.IntegerItem == nil {
+	if o == nil {
 		var ret int32
 		return ret
 	}
-	return *o.IntegerItem
-}
-
-// GetIntegerItemOk returns a tuple with the IntegerItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderExample) GetIntegerItemOk() (int32, bool) {
-	if o == nil || o.IntegerItem == nil {
-		var ret int32
-		return ret, false
-	}
-	return *o.IntegerItem, true
-}
-
-// HasIntegerItem returns a boolean if a field has been set.
-func (o *TypeHolderExample) HasIntegerItem() bool {
-	if o != nil && o.IntegerItem != nil {
-		return true
-	}
 
-	return false
+	return o.IntegerItem
 }
 
-// SetIntegerItem gets a reference to the given int32 and assigns it to the IntegerItem field.
+// SetIntegerItem sets field value
 func (o *TypeHolderExample) SetIntegerItem(v int32) {
-	o.IntegerItem = &v
+	o.IntegerItem = v
 }
 
-// GetBoolItem returns the BoolItem field if non-nil, zero value otherwise.
+// GetBoolItem returns the BoolItem field value
 func (o *TypeHolderExample) GetBoolItem() bool {
-	if o == nil || o.BoolItem == nil {
+	if o == nil {
 		var ret bool
 		return ret
 	}
-	return *o.BoolItem
-}
-
-// GetBoolItemOk returns a tuple with the BoolItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderExample) GetBoolItemOk() (bool, bool) {
-	if o == nil || o.BoolItem == nil {
-		var ret bool
-		return ret, false
-	}
-	return *o.BoolItem, true
-}
-
-// HasBoolItem returns a boolean if a field has been set.
-func (o *TypeHolderExample) HasBoolItem() bool {
-	if o != nil && o.BoolItem != nil {
-		return true
-	}
 
-	return false
+	return o.BoolItem
 }
 
-// SetBoolItem gets a reference to the given bool and assigns it to the BoolItem field.
+// SetBoolItem sets field value
 func (o *TypeHolderExample) SetBoolItem(v bool) {
-	o.BoolItem = &v
+	o.BoolItem = v
 }
 
-// GetArrayItem returns the ArrayItem field if non-nil, zero value otherwise.
+// GetArrayItem returns the ArrayItem field value
 func (o *TypeHolderExample) GetArrayItem() []int32 {
-	if o == nil || o.ArrayItem == nil {
+	if o == nil {
 		var ret []int32
 		return ret
 	}
-	return *o.ArrayItem
-}
 
-// GetArrayItemOk returns a tuple with the ArrayItem field if it's non-nil, zero value otherwise
-// and a boolean to check if the value has been set.
-func (o *TypeHolderExample) GetArrayItemOk() ([]int32, bool) {
-	if o == nil || o.ArrayItem == nil {
-		var ret []int32
-		return ret, false
-	}
-	return *o.ArrayItem, true
+	return o.ArrayItem
 }
 
-// HasArrayItem returns a boolean if a field has been set.
-func (o *TypeHolderExample) HasArrayItem() bool {
-	if o != nil && o.ArrayItem != nil {
-		return true
-	}
-
-	return false
+// SetArrayItem sets field value
+func (o *TypeHolderExample) SetArrayItem(v []int32) {
+	o.ArrayItem = v
 }
 
-// SetArrayItem gets a reference to the given []int32 and assigns it to the ArrayItem field.
-func (o *TypeHolderExample) SetArrayItem(v []int32) {
-	o.ArrayItem = &v
+type NullableTypeHolderExample struct {
+	Value TypeHolderExample
+	ExplicitNull bool
 }
 
+func (v NullableTypeHolderExample) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o TypeHolderExample) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.StringItem == nil {
-		return nil, errors.New("StringItem is required and not nullable, but was not set on TypeHolderExample")
-	}
-	if o.StringItem != nil {
-		toSerialize["string_item"] = o.StringItem
-	}
-	if o.NumberItem == nil {
-		return nil, errors.New("NumberItem is required and not nullable, but was not set on TypeHolderExample")
-	}
-	if o.NumberItem != nil {
-		toSerialize["number_item"] = o.NumberItem
-	}
-	if o.FloatItem == nil {
-		return nil, errors.New("FloatItem is required and not nullable, but was not set on TypeHolderExample")
-	}
-	if o.FloatItem != nil {
-		toSerialize["float_item"] = o.FloatItem
+func (v *NullableTypeHolderExample) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.IntegerItem == nil {
-		return nil, errors.New("IntegerItem is required and not nullable, but was not set on TypeHolderExample")
-	}
-	if o.IntegerItem != nil {
-		toSerialize["integer_item"] = o.IntegerItem
-	}
-	if o.BoolItem == nil {
-		return nil, errors.New("BoolItem is required and not nullable, but was not set on TypeHolderExample")
-	}
-	if o.BoolItem != nil {
-		toSerialize["bool_item"] = o.BoolItem
-	}
-	if o.ArrayItem == nil {
-		return nil, errors.New("ArrayItem is required and not nullable, but was not set on TypeHolderExample")
-	}
-	if o.ArrayItem != nil {
-		toSerialize["array_item"] = o.ArrayItem
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_user.go b/samples/client/petstore/go-experimental/go-petstore/model_user.go
index 174a791aa728..4411c284794d 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_user.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_user.go
@@ -8,31 +8,26 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // User struct for User
 type User struct {
 	Id *int64 `json:"id,omitempty"`
-
 	Username *string `json:"username,omitempty"`
-
 	FirstName *string `json:"firstName,omitempty"`
-
 	LastName *string `json:"lastName,omitempty"`
-
 	Email *string `json:"email,omitempty"`
-
 	Password *string `json:"password,omitempty"`
-
 	Phone *string `json:"phone,omitempty"`
-
 	// User Status
 	UserStatus *int32 `json:"userStatus,omitempty"`
-
 }
 
-// GetId returns the Id field if non-nil, zero value otherwise.
+// GetId returns the Id field value if set, zero value otherwise.
 func (o *User) GetId() int64 {
 	if o == nil || o.Id == nil {
 		var ret int64
@@ -41,7 +36,7 @@ func (o *User) GetId() int64 {
 	return *o.Id
 }
 
-// GetIdOk returns a tuple with the Id field if it's non-nil, zero value otherwise
+// GetIdOk returns a tuple with the Id field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *User) GetIdOk() (int64, bool) {
 	if o == nil || o.Id == nil {
@@ -65,7 +60,7 @@ func (o *User) SetId(v int64) {
 	o.Id = &v
 }
 
-// GetUsername returns the Username field if non-nil, zero value otherwise.
+// GetUsername returns the Username field value if set, zero value otherwise.
 func (o *User) GetUsername() string {
 	if o == nil || o.Username == nil {
 		var ret string
@@ -74,7 +69,7 @@ func (o *User) GetUsername() string {
 	return *o.Username
 }
 
-// GetUsernameOk returns a tuple with the Username field if it's non-nil, zero value otherwise
+// GetUsernameOk returns a tuple with the Username field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *User) GetUsernameOk() (string, bool) {
 	if o == nil || o.Username == nil {
@@ -98,7 +93,7 @@ func (o *User) SetUsername(v string) {
 	o.Username = &v
 }
 
-// GetFirstName returns the FirstName field if non-nil, zero value otherwise.
+// GetFirstName returns the FirstName field value if set, zero value otherwise.
 func (o *User) GetFirstName() string {
 	if o == nil || o.FirstName == nil {
 		var ret string
@@ -107,7 +102,7 @@ func (o *User) GetFirstName() string {
 	return *o.FirstName
 }
 
-// GetFirstNameOk returns a tuple with the FirstName field if it's non-nil, zero value otherwise
+// GetFirstNameOk returns a tuple with the FirstName field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *User) GetFirstNameOk() (string, bool) {
 	if o == nil || o.FirstName == nil {
@@ -131,7 +126,7 @@ func (o *User) SetFirstName(v string) {
 	o.FirstName = &v
 }
 
-// GetLastName returns the LastName field if non-nil, zero value otherwise.
+// GetLastName returns the LastName field value if set, zero value otherwise.
 func (o *User) GetLastName() string {
 	if o == nil || o.LastName == nil {
 		var ret string
@@ -140,7 +135,7 @@ func (o *User) GetLastName() string {
 	return *o.LastName
 }
 
-// GetLastNameOk returns a tuple with the LastName field if it's non-nil, zero value otherwise
+// GetLastNameOk returns a tuple with the LastName field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *User) GetLastNameOk() (string, bool) {
 	if o == nil || o.LastName == nil {
@@ -164,7 +159,7 @@ func (o *User) SetLastName(v string) {
 	o.LastName = &v
 }
 
-// GetEmail returns the Email field if non-nil, zero value otherwise.
+// GetEmail returns the Email field value if set, zero value otherwise.
 func (o *User) GetEmail() string {
 	if o == nil || o.Email == nil {
 		var ret string
@@ -173,7 +168,7 @@ func (o *User) GetEmail() string {
 	return *o.Email
 }
 
-// GetEmailOk returns a tuple with the Email field if it's non-nil, zero value otherwise
+// GetEmailOk returns a tuple with the Email field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *User) GetEmailOk() (string, bool) {
 	if o == nil || o.Email == nil {
@@ -197,7 +192,7 @@ func (o *User) SetEmail(v string) {
 	o.Email = &v
 }
 
-// GetPassword returns the Password field if non-nil, zero value otherwise.
+// GetPassword returns the Password field value if set, zero value otherwise.
 func (o *User) GetPassword() string {
 	if o == nil || o.Password == nil {
 		var ret string
@@ -206,7 +201,7 @@ func (o *User) GetPassword() string {
 	return *o.Password
 }
 
-// GetPasswordOk returns a tuple with the Password field if it's non-nil, zero value otherwise
+// GetPasswordOk returns a tuple with the Password field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *User) GetPasswordOk() (string, bool) {
 	if o == nil || o.Password == nil {
@@ -230,7 +225,7 @@ func (o *User) SetPassword(v string) {
 	o.Password = &v
 }
 
-// GetPhone returns the Phone field if non-nil, zero value otherwise.
+// GetPhone returns the Phone field value if set, zero value otherwise.
 func (o *User) GetPhone() string {
 	if o == nil || o.Phone == nil {
 		var ret string
@@ -239,7 +234,7 @@ func (o *User) GetPhone() string {
 	return *o.Phone
 }
 
-// GetPhoneOk returns a tuple with the Phone field if it's non-nil, zero value otherwise
+// GetPhoneOk returns a tuple with the Phone field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *User) GetPhoneOk() (string, bool) {
 	if o == nil || o.Phone == nil {
@@ -263,7 +258,7 @@ func (o *User) SetPhone(v string) {
 	o.Phone = &v
 }
 
-// GetUserStatus returns the UserStatus field if non-nil, zero value otherwise.
+// GetUserStatus returns the UserStatus field value if set, zero value otherwise.
 func (o *User) GetUserStatus() int32 {
 	if o == nil || o.UserStatus == nil {
 		var ret int32
@@ -272,7 +267,7 @@ func (o *User) GetUserStatus() int32 {
 	return *o.UserStatus
 }
 
-// GetUserStatusOk returns a tuple with the UserStatus field if it's non-nil, zero value otherwise
+// GetUserStatusOk returns a tuple with the UserStatus field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *User) GetUserStatusOk() (int32, bool) {
 	if o == nil || o.UserStatus == nil {
@@ -296,35 +291,26 @@ func (o *User) SetUserStatus(v int32) {
 	o.UserStatus = &v
 }
 
+type NullableUser struct {
+	Value User
+	ExplicitNull bool
+}
+
+func (v NullableUser) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o User) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.Id != nil {
-		toSerialize["id"] = o.Id
-	}
-	if o.Username != nil {
-		toSerialize["username"] = o.Username
-	}
-	if o.FirstName != nil {
-		toSerialize["firstName"] = o.FirstName
-	}
-	if o.LastName != nil {
-		toSerialize["lastName"] = o.LastName
-	}
-	if o.Email != nil {
-		toSerialize["email"] = o.Email
+func (v *NullableUser) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.Password != nil {
-		toSerialize["password"] = o.Password
-	}
-	if o.Phone != nil {
-		toSerialize["phone"] = o.Phone
-	}
-	if o.UserStatus != nil {
-		toSerialize["userStatus"] = o.UserStatus
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/model_xml_item.go b/samples/client/petstore/go-experimental/go-petstore/model_xml_item.go
index e1b9efa8e0b9..ddf16b84247f 100644
--- a/samples/client/petstore/go-experimental/go-petstore/model_xml_item.go
+++ b/samples/client/petstore/go-experimental/go-petstore/model_xml_item.go
@@ -8,72 +8,46 @@
  */
 
 package petstore
+
 import (
+	"bytes"
 	"encoding/json"
 )
+
 // XmlItem struct for XmlItem
 type XmlItem struct {
 	AttributeString *string `json:"attribute_string,omitempty"`
-
 	AttributeNumber *float32 `json:"attribute_number,omitempty"`
-
 	AttributeInteger *int32 `json:"attribute_integer,omitempty"`
-
 	AttributeBoolean *bool `json:"attribute_boolean,omitempty"`
-
 	WrappedArray *[]int32 `json:"wrapped_array,omitempty"`
-
 	NameString *string `json:"name_string,omitempty"`
-
 	NameNumber *float32 `json:"name_number,omitempty"`
-
 	NameInteger *int32 `json:"name_integer,omitempty"`
-
 	NameBoolean *bool `json:"name_boolean,omitempty"`
-
 	NameArray *[]int32 `json:"name_array,omitempty"`
-
 	NameWrappedArray *[]int32 `json:"name_wrapped_array,omitempty"`
-
 	PrefixString *string `json:"prefix_string,omitempty"`
-
 	PrefixNumber *float32 `json:"prefix_number,omitempty"`
-
 	PrefixInteger *int32 `json:"prefix_integer,omitempty"`
-
 	PrefixBoolean *bool `json:"prefix_boolean,omitempty"`
-
 	PrefixArray *[]int32 `json:"prefix_array,omitempty"`
-
 	PrefixWrappedArray *[]int32 `json:"prefix_wrapped_array,omitempty"`
-
 	NamespaceString *string `json:"namespace_string,omitempty"`
-
 	NamespaceNumber *float32 `json:"namespace_number,omitempty"`
-
 	NamespaceInteger *int32 `json:"namespace_integer,omitempty"`
-
 	NamespaceBoolean *bool `json:"namespace_boolean,omitempty"`
-
 	NamespaceArray *[]int32 `json:"namespace_array,omitempty"`
-
 	NamespaceWrappedArray *[]int32 `json:"namespace_wrapped_array,omitempty"`
-
 	PrefixNsString *string `json:"prefix_ns_string,omitempty"`
-
 	PrefixNsNumber *float32 `json:"prefix_ns_number,omitempty"`
-
 	PrefixNsInteger *int32 `json:"prefix_ns_integer,omitempty"`
-
 	PrefixNsBoolean *bool `json:"prefix_ns_boolean,omitempty"`
-
 	PrefixNsArray *[]int32 `json:"prefix_ns_array,omitempty"`
-
 	PrefixNsWrappedArray *[]int32 `json:"prefix_ns_wrapped_array,omitempty"`
-
 }
 
-// GetAttributeString returns the AttributeString field if non-nil, zero value otherwise.
+// GetAttributeString returns the AttributeString field value if set, zero value otherwise.
 func (o *XmlItem) GetAttributeString() string {
 	if o == nil || o.AttributeString == nil {
 		var ret string
@@ -82,7 +56,7 @@ func (o *XmlItem) GetAttributeString() string {
 	return *o.AttributeString
 }
 
-// GetAttributeStringOk returns a tuple with the AttributeString field if it's non-nil, zero value otherwise
+// GetAttributeStringOk returns a tuple with the AttributeString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetAttributeStringOk() (string, bool) {
 	if o == nil || o.AttributeString == nil {
@@ -106,7 +80,7 @@ func (o *XmlItem) SetAttributeString(v string) {
 	o.AttributeString = &v
 }
 
-// GetAttributeNumber returns the AttributeNumber field if non-nil, zero value otherwise.
+// GetAttributeNumber returns the AttributeNumber field value if set, zero value otherwise.
 func (o *XmlItem) GetAttributeNumber() float32 {
 	if o == nil || o.AttributeNumber == nil {
 		var ret float32
@@ -115,7 +89,7 @@ func (o *XmlItem) GetAttributeNumber() float32 {
 	return *o.AttributeNumber
 }
 
-// GetAttributeNumberOk returns a tuple with the AttributeNumber field if it's non-nil, zero value otherwise
+// GetAttributeNumberOk returns a tuple with the AttributeNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetAttributeNumberOk() (float32, bool) {
 	if o == nil || o.AttributeNumber == nil {
@@ -139,7 +113,7 @@ func (o *XmlItem) SetAttributeNumber(v float32) {
 	o.AttributeNumber = &v
 }
 
-// GetAttributeInteger returns the AttributeInteger field if non-nil, zero value otherwise.
+// GetAttributeInteger returns the AttributeInteger field value if set, zero value otherwise.
 func (o *XmlItem) GetAttributeInteger() int32 {
 	if o == nil || o.AttributeInteger == nil {
 		var ret int32
@@ -148,7 +122,7 @@ func (o *XmlItem) GetAttributeInteger() int32 {
 	return *o.AttributeInteger
 }
 
-// GetAttributeIntegerOk returns a tuple with the AttributeInteger field if it's non-nil, zero value otherwise
+// GetAttributeIntegerOk returns a tuple with the AttributeInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetAttributeIntegerOk() (int32, bool) {
 	if o == nil || o.AttributeInteger == nil {
@@ -172,7 +146,7 @@ func (o *XmlItem) SetAttributeInteger(v int32) {
 	o.AttributeInteger = &v
 }
 
-// GetAttributeBoolean returns the AttributeBoolean field if non-nil, zero value otherwise.
+// GetAttributeBoolean returns the AttributeBoolean field value if set, zero value otherwise.
 func (o *XmlItem) GetAttributeBoolean() bool {
 	if o == nil || o.AttributeBoolean == nil {
 		var ret bool
@@ -181,7 +155,7 @@ func (o *XmlItem) GetAttributeBoolean() bool {
 	return *o.AttributeBoolean
 }
 
-// GetAttributeBooleanOk returns a tuple with the AttributeBoolean field if it's non-nil, zero value otherwise
+// GetAttributeBooleanOk returns a tuple with the AttributeBoolean field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetAttributeBooleanOk() (bool, bool) {
 	if o == nil || o.AttributeBoolean == nil {
@@ -205,7 +179,7 @@ func (o *XmlItem) SetAttributeBoolean(v bool) {
 	o.AttributeBoolean = &v
 }
 
-// GetWrappedArray returns the WrappedArray field if non-nil, zero value otherwise.
+// GetWrappedArray returns the WrappedArray field value if set, zero value otherwise.
 func (o *XmlItem) GetWrappedArray() []int32 {
 	if o == nil || o.WrappedArray == nil {
 		var ret []int32
@@ -214,7 +188,7 @@ func (o *XmlItem) GetWrappedArray() []int32 {
 	return *o.WrappedArray
 }
 
-// GetWrappedArrayOk returns a tuple with the WrappedArray field if it's non-nil, zero value otherwise
+// GetWrappedArrayOk returns a tuple with the WrappedArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetWrappedArrayOk() ([]int32, bool) {
 	if o == nil || o.WrappedArray == nil {
@@ -238,7 +212,7 @@ func (o *XmlItem) SetWrappedArray(v []int32) {
 	o.WrappedArray = &v
 }
 
-// GetNameString returns the NameString field if non-nil, zero value otherwise.
+// GetNameString returns the NameString field value if set, zero value otherwise.
 func (o *XmlItem) GetNameString() string {
 	if o == nil || o.NameString == nil {
 		var ret string
@@ -247,7 +221,7 @@ func (o *XmlItem) GetNameString() string {
 	return *o.NameString
 }
 
-// GetNameStringOk returns a tuple with the NameString field if it's non-nil, zero value otherwise
+// GetNameStringOk returns a tuple with the NameString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNameStringOk() (string, bool) {
 	if o == nil || o.NameString == nil {
@@ -271,7 +245,7 @@ func (o *XmlItem) SetNameString(v string) {
 	o.NameString = &v
 }
 
-// GetNameNumber returns the NameNumber field if non-nil, zero value otherwise.
+// GetNameNumber returns the NameNumber field value if set, zero value otherwise.
 func (o *XmlItem) GetNameNumber() float32 {
 	if o == nil || o.NameNumber == nil {
 		var ret float32
@@ -280,7 +254,7 @@ func (o *XmlItem) GetNameNumber() float32 {
 	return *o.NameNumber
 }
 
-// GetNameNumberOk returns a tuple with the NameNumber field if it's non-nil, zero value otherwise
+// GetNameNumberOk returns a tuple with the NameNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNameNumberOk() (float32, bool) {
 	if o == nil || o.NameNumber == nil {
@@ -304,7 +278,7 @@ func (o *XmlItem) SetNameNumber(v float32) {
 	o.NameNumber = &v
 }
 
-// GetNameInteger returns the NameInteger field if non-nil, zero value otherwise.
+// GetNameInteger returns the NameInteger field value if set, zero value otherwise.
 func (o *XmlItem) GetNameInteger() int32 {
 	if o == nil || o.NameInteger == nil {
 		var ret int32
@@ -313,7 +287,7 @@ func (o *XmlItem) GetNameInteger() int32 {
 	return *o.NameInteger
 }
 
-// GetNameIntegerOk returns a tuple with the NameInteger field if it's non-nil, zero value otherwise
+// GetNameIntegerOk returns a tuple with the NameInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNameIntegerOk() (int32, bool) {
 	if o == nil || o.NameInteger == nil {
@@ -337,7 +311,7 @@ func (o *XmlItem) SetNameInteger(v int32) {
 	o.NameInteger = &v
 }
 
-// GetNameBoolean returns the NameBoolean field if non-nil, zero value otherwise.
+// GetNameBoolean returns the NameBoolean field value if set, zero value otherwise.
 func (o *XmlItem) GetNameBoolean() bool {
 	if o == nil || o.NameBoolean == nil {
 		var ret bool
@@ -346,7 +320,7 @@ func (o *XmlItem) GetNameBoolean() bool {
 	return *o.NameBoolean
 }
 
-// GetNameBooleanOk returns a tuple with the NameBoolean field if it's non-nil, zero value otherwise
+// GetNameBooleanOk returns a tuple with the NameBoolean field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNameBooleanOk() (bool, bool) {
 	if o == nil || o.NameBoolean == nil {
@@ -370,7 +344,7 @@ func (o *XmlItem) SetNameBoolean(v bool) {
 	o.NameBoolean = &v
 }
 
-// GetNameArray returns the NameArray field if non-nil, zero value otherwise.
+// GetNameArray returns the NameArray field value if set, zero value otherwise.
 func (o *XmlItem) GetNameArray() []int32 {
 	if o == nil || o.NameArray == nil {
 		var ret []int32
@@ -379,7 +353,7 @@ func (o *XmlItem) GetNameArray() []int32 {
 	return *o.NameArray
 }
 
-// GetNameArrayOk returns a tuple with the NameArray field if it's non-nil, zero value otherwise
+// GetNameArrayOk returns a tuple with the NameArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNameArrayOk() ([]int32, bool) {
 	if o == nil || o.NameArray == nil {
@@ -403,7 +377,7 @@ func (o *XmlItem) SetNameArray(v []int32) {
 	o.NameArray = &v
 }
 
-// GetNameWrappedArray returns the NameWrappedArray field if non-nil, zero value otherwise.
+// GetNameWrappedArray returns the NameWrappedArray field value if set, zero value otherwise.
 func (o *XmlItem) GetNameWrappedArray() []int32 {
 	if o == nil || o.NameWrappedArray == nil {
 		var ret []int32
@@ -412,7 +386,7 @@ func (o *XmlItem) GetNameWrappedArray() []int32 {
 	return *o.NameWrappedArray
 }
 
-// GetNameWrappedArrayOk returns a tuple with the NameWrappedArray field if it's non-nil, zero value otherwise
+// GetNameWrappedArrayOk returns a tuple with the NameWrappedArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNameWrappedArrayOk() ([]int32, bool) {
 	if o == nil || o.NameWrappedArray == nil {
@@ -436,7 +410,7 @@ func (o *XmlItem) SetNameWrappedArray(v []int32) {
 	o.NameWrappedArray = &v
 }
 
-// GetPrefixString returns the PrefixString field if non-nil, zero value otherwise.
+// GetPrefixString returns the PrefixString field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixString() string {
 	if o == nil || o.PrefixString == nil {
 		var ret string
@@ -445,7 +419,7 @@ func (o *XmlItem) GetPrefixString() string {
 	return *o.PrefixString
 }
 
-// GetPrefixStringOk returns a tuple with the PrefixString field if it's non-nil, zero value otherwise
+// GetPrefixStringOk returns a tuple with the PrefixString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixStringOk() (string, bool) {
 	if o == nil || o.PrefixString == nil {
@@ -469,7 +443,7 @@ func (o *XmlItem) SetPrefixString(v string) {
 	o.PrefixString = &v
 }
 
-// GetPrefixNumber returns the PrefixNumber field if non-nil, zero value otherwise.
+// GetPrefixNumber returns the PrefixNumber field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixNumber() float32 {
 	if o == nil || o.PrefixNumber == nil {
 		var ret float32
@@ -478,7 +452,7 @@ func (o *XmlItem) GetPrefixNumber() float32 {
 	return *o.PrefixNumber
 }
 
-// GetPrefixNumberOk returns a tuple with the PrefixNumber field if it's non-nil, zero value otherwise
+// GetPrefixNumberOk returns a tuple with the PrefixNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixNumberOk() (float32, bool) {
 	if o == nil || o.PrefixNumber == nil {
@@ -502,7 +476,7 @@ func (o *XmlItem) SetPrefixNumber(v float32) {
 	o.PrefixNumber = &v
 }
 
-// GetPrefixInteger returns the PrefixInteger field if non-nil, zero value otherwise.
+// GetPrefixInteger returns the PrefixInteger field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixInteger() int32 {
 	if o == nil || o.PrefixInteger == nil {
 		var ret int32
@@ -511,7 +485,7 @@ func (o *XmlItem) GetPrefixInteger() int32 {
 	return *o.PrefixInteger
 }
 
-// GetPrefixIntegerOk returns a tuple with the PrefixInteger field if it's non-nil, zero value otherwise
+// GetPrefixIntegerOk returns a tuple with the PrefixInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixIntegerOk() (int32, bool) {
 	if o == nil || o.PrefixInteger == nil {
@@ -535,7 +509,7 @@ func (o *XmlItem) SetPrefixInteger(v int32) {
 	o.PrefixInteger = &v
 }
 
-// GetPrefixBoolean returns the PrefixBoolean field if non-nil, zero value otherwise.
+// GetPrefixBoolean returns the PrefixBoolean field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixBoolean() bool {
 	if o == nil || o.PrefixBoolean == nil {
 		var ret bool
@@ -544,7 +518,7 @@ func (o *XmlItem) GetPrefixBoolean() bool {
 	return *o.PrefixBoolean
 }
 
-// GetPrefixBooleanOk returns a tuple with the PrefixBoolean field if it's non-nil, zero value otherwise
+// GetPrefixBooleanOk returns a tuple with the PrefixBoolean field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixBooleanOk() (bool, bool) {
 	if o == nil || o.PrefixBoolean == nil {
@@ -568,7 +542,7 @@ func (o *XmlItem) SetPrefixBoolean(v bool) {
 	o.PrefixBoolean = &v
 }
 
-// GetPrefixArray returns the PrefixArray field if non-nil, zero value otherwise.
+// GetPrefixArray returns the PrefixArray field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixArray() []int32 {
 	if o == nil || o.PrefixArray == nil {
 		var ret []int32
@@ -577,7 +551,7 @@ func (o *XmlItem) GetPrefixArray() []int32 {
 	return *o.PrefixArray
 }
 
-// GetPrefixArrayOk returns a tuple with the PrefixArray field if it's non-nil, zero value otherwise
+// GetPrefixArrayOk returns a tuple with the PrefixArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixArrayOk() ([]int32, bool) {
 	if o == nil || o.PrefixArray == nil {
@@ -601,7 +575,7 @@ func (o *XmlItem) SetPrefixArray(v []int32) {
 	o.PrefixArray = &v
 }
 
-// GetPrefixWrappedArray returns the PrefixWrappedArray field if non-nil, zero value otherwise.
+// GetPrefixWrappedArray returns the PrefixWrappedArray field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixWrappedArray() []int32 {
 	if o == nil || o.PrefixWrappedArray == nil {
 		var ret []int32
@@ -610,7 +584,7 @@ func (o *XmlItem) GetPrefixWrappedArray() []int32 {
 	return *o.PrefixWrappedArray
 }
 
-// GetPrefixWrappedArrayOk returns a tuple with the PrefixWrappedArray field if it's non-nil, zero value otherwise
+// GetPrefixWrappedArrayOk returns a tuple with the PrefixWrappedArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixWrappedArrayOk() ([]int32, bool) {
 	if o == nil || o.PrefixWrappedArray == nil {
@@ -634,7 +608,7 @@ func (o *XmlItem) SetPrefixWrappedArray(v []int32) {
 	o.PrefixWrappedArray = &v
 }
 
-// GetNamespaceString returns the NamespaceString field if non-nil, zero value otherwise.
+// GetNamespaceString returns the NamespaceString field value if set, zero value otherwise.
 func (o *XmlItem) GetNamespaceString() string {
 	if o == nil || o.NamespaceString == nil {
 		var ret string
@@ -643,7 +617,7 @@ func (o *XmlItem) GetNamespaceString() string {
 	return *o.NamespaceString
 }
 
-// GetNamespaceStringOk returns a tuple with the NamespaceString field if it's non-nil, zero value otherwise
+// GetNamespaceStringOk returns a tuple with the NamespaceString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNamespaceStringOk() (string, bool) {
 	if o == nil || o.NamespaceString == nil {
@@ -667,7 +641,7 @@ func (o *XmlItem) SetNamespaceString(v string) {
 	o.NamespaceString = &v
 }
 
-// GetNamespaceNumber returns the NamespaceNumber field if non-nil, zero value otherwise.
+// GetNamespaceNumber returns the NamespaceNumber field value if set, zero value otherwise.
 func (o *XmlItem) GetNamespaceNumber() float32 {
 	if o == nil || o.NamespaceNumber == nil {
 		var ret float32
@@ -676,7 +650,7 @@ func (o *XmlItem) GetNamespaceNumber() float32 {
 	return *o.NamespaceNumber
 }
 
-// GetNamespaceNumberOk returns a tuple with the NamespaceNumber field if it's non-nil, zero value otherwise
+// GetNamespaceNumberOk returns a tuple with the NamespaceNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNamespaceNumberOk() (float32, bool) {
 	if o == nil || o.NamespaceNumber == nil {
@@ -700,7 +674,7 @@ func (o *XmlItem) SetNamespaceNumber(v float32) {
 	o.NamespaceNumber = &v
 }
 
-// GetNamespaceInteger returns the NamespaceInteger field if non-nil, zero value otherwise.
+// GetNamespaceInteger returns the NamespaceInteger field value if set, zero value otherwise.
 func (o *XmlItem) GetNamespaceInteger() int32 {
 	if o == nil || o.NamespaceInteger == nil {
 		var ret int32
@@ -709,7 +683,7 @@ func (o *XmlItem) GetNamespaceInteger() int32 {
 	return *o.NamespaceInteger
 }
 
-// GetNamespaceIntegerOk returns a tuple with the NamespaceInteger field if it's non-nil, zero value otherwise
+// GetNamespaceIntegerOk returns a tuple with the NamespaceInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNamespaceIntegerOk() (int32, bool) {
 	if o == nil || o.NamespaceInteger == nil {
@@ -733,7 +707,7 @@ func (o *XmlItem) SetNamespaceInteger(v int32) {
 	o.NamespaceInteger = &v
 }
 
-// GetNamespaceBoolean returns the NamespaceBoolean field if non-nil, zero value otherwise.
+// GetNamespaceBoolean returns the NamespaceBoolean field value if set, zero value otherwise.
 func (o *XmlItem) GetNamespaceBoolean() bool {
 	if o == nil || o.NamespaceBoolean == nil {
 		var ret bool
@@ -742,7 +716,7 @@ func (o *XmlItem) GetNamespaceBoolean() bool {
 	return *o.NamespaceBoolean
 }
 
-// GetNamespaceBooleanOk returns a tuple with the NamespaceBoolean field if it's non-nil, zero value otherwise
+// GetNamespaceBooleanOk returns a tuple with the NamespaceBoolean field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNamespaceBooleanOk() (bool, bool) {
 	if o == nil || o.NamespaceBoolean == nil {
@@ -766,7 +740,7 @@ func (o *XmlItem) SetNamespaceBoolean(v bool) {
 	o.NamespaceBoolean = &v
 }
 
-// GetNamespaceArray returns the NamespaceArray field if non-nil, zero value otherwise.
+// GetNamespaceArray returns the NamespaceArray field value if set, zero value otherwise.
 func (o *XmlItem) GetNamespaceArray() []int32 {
 	if o == nil || o.NamespaceArray == nil {
 		var ret []int32
@@ -775,7 +749,7 @@ func (o *XmlItem) GetNamespaceArray() []int32 {
 	return *o.NamespaceArray
 }
 
-// GetNamespaceArrayOk returns a tuple with the NamespaceArray field if it's non-nil, zero value otherwise
+// GetNamespaceArrayOk returns a tuple with the NamespaceArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNamespaceArrayOk() ([]int32, bool) {
 	if o == nil || o.NamespaceArray == nil {
@@ -799,7 +773,7 @@ func (o *XmlItem) SetNamespaceArray(v []int32) {
 	o.NamespaceArray = &v
 }
 
-// GetNamespaceWrappedArray returns the NamespaceWrappedArray field if non-nil, zero value otherwise.
+// GetNamespaceWrappedArray returns the NamespaceWrappedArray field value if set, zero value otherwise.
 func (o *XmlItem) GetNamespaceWrappedArray() []int32 {
 	if o == nil || o.NamespaceWrappedArray == nil {
 		var ret []int32
@@ -808,7 +782,7 @@ func (o *XmlItem) GetNamespaceWrappedArray() []int32 {
 	return *o.NamespaceWrappedArray
 }
 
-// GetNamespaceWrappedArrayOk returns a tuple with the NamespaceWrappedArray field if it's non-nil, zero value otherwise
+// GetNamespaceWrappedArrayOk returns a tuple with the NamespaceWrappedArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetNamespaceWrappedArrayOk() ([]int32, bool) {
 	if o == nil || o.NamespaceWrappedArray == nil {
@@ -832,7 +806,7 @@ func (o *XmlItem) SetNamespaceWrappedArray(v []int32) {
 	o.NamespaceWrappedArray = &v
 }
 
-// GetPrefixNsString returns the PrefixNsString field if non-nil, zero value otherwise.
+// GetPrefixNsString returns the PrefixNsString field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixNsString() string {
 	if o == nil || o.PrefixNsString == nil {
 		var ret string
@@ -841,7 +815,7 @@ func (o *XmlItem) GetPrefixNsString() string {
 	return *o.PrefixNsString
 }
 
-// GetPrefixNsStringOk returns a tuple with the PrefixNsString field if it's non-nil, zero value otherwise
+// GetPrefixNsStringOk returns a tuple with the PrefixNsString field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixNsStringOk() (string, bool) {
 	if o == nil || o.PrefixNsString == nil {
@@ -865,7 +839,7 @@ func (o *XmlItem) SetPrefixNsString(v string) {
 	o.PrefixNsString = &v
 }
 
-// GetPrefixNsNumber returns the PrefixNsNumber field if non-nil, zero value otherwise.
+// GetPrefixNsNumber returns the PrefixNsNumber field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixNsNumber() float32 {
 	if o == nil || o.PrefixNsNumber == nil {
 		var ret float32
@@ -874,7 +848,7 @@ func (o *XmlItem) GetPrefixNsNumber() float32 {
 	return *o.PrefixNsNumber
 }
 
-// GetPrefixNsNumberOk returns a tuple with the PrefixNsNumber field if it's non-nil, zero value otherwise
+// GetPrefixNsNumberOk returns a tuple with the PrefixNsNumber field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixNsNumberOk() (float32, bool) {
 	if o == nil || o.PrefixNsNumber == nil {
@@ -898,7 +872,7 @@ func (o *XmlItem) SetPrefixNsNumber(v float32) {
 	o.PrefixNsNumber = &v
 }
 
-// GetPrefixNsInteger returns the PrefixNsInteger field if non-nil, zero value otherwise.
+// GetPrefixNsInteger returns the PrefixNsInteger field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixNsInteger() int32 {
 	if o == nil || o.PrefixNsInteger == nil {
 		var ret int32
@@ -907,7 +881,7 @@ func (o *XmlItem) GetPrefixNsInteger() int32 {
 	return *o.PrefixNsInteger
 }
 
-// GetPrefixNsIntegerOk returns a tuple with the PrefixNsInteger field if it's non-nil, zero value otherwise
+// GetPrefixNsIntegerOk returns a tuple with the PrefixNsInteger field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixNsIntegerOk() (int32, bool) {
 	if o == nil || o.PrefixNsInteger == nil {
@@ -931,7 +905,7 @@ func (o *XmlItem) SetPrefixNsInteger(v int32) {
 	o.PrefixNsInteger = &v
 }
 
-// GetPrefixNsBoolean returns the PrefixNsBoolean field if non-nil, zero value otherwise.
+// GetPrefixNsBoolean returns the PrefixNsBoolean field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixNsBoolean() bool {
 	if o == nil || o.PrefixNsBoolean == nil {
 		var ret bool
@@ -940,7 +914,7 @@ func (o *XmlItem) GetPrefixNsBoolean() bool {
 	return *o.PrefixNsBoolean
 }
 
-// GetPrefixNsBooleanOk returns a tuple with the PrefixNsBoolean field if it's non-nil, zero value otherwise
+// GetPrefixNsBooleanOk returns a tuple with the PrefixNsBoolean field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixNsBooleanOk() (bool, bool) {
 	if o == nil || o.PrefixNsBoolean == nil {
@@ -964,7 +938,7 @@ func (o *XmlItem) SetPrefixNsBoolean(v bool) {
 	o.PrefixNsBoolean = &v
 }
 
-// GetPrefixNsArray returns the PrefixNsArray field if non-nil, zero value otherwise.
+// GetPrefixNsArray returns the PrefixNsArray field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixNsArray() []int32 {
 	if o == nil || o.PrefixNsArray == nil {
 		var ret []int32
@@ -973,7 +947,7 @@ func (o *XmlItem) GetPrefixNsArray() []int32 {
 	return *o.PrefixNsArray
 }
 
-// GetPrefixNsArrayOk returns a tuple with the PrefixNsArray field if it's non-nil, zero value otherwise
+// GetPrefixNsArrayOk returns a tuple with the PrefixNsArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixNsArrayOk() ([]int32, bool) {
 	if o == nil || o.PrefixNsArray == nil {
@@ -997,7 +971,7 @@ func (o *XmlItem) SetPrefixNsArray(v []int32) {
 	o.PrefixNsArray = &v
 }
 
-// GetPrefixNsWrappedArray returns the PrefixNsWrappedArray field if non-nil, zero value otherwise.
+// GetPrefixNsWrappedArray returns the PrefixNsWrappedArray field value if set, zero value otherwise.
 func (o *XmlItem) GetPrefixNsWrappedArray() []int32 {
 	if o == nil || o.PrefixNsWrappedArray == nil {
 		var ret []int32
@@ -1006,7 +980,7 @@ func (o *XmlItem) GetPrefixNsWrappedArray() []int32 {
 	return *o.PrefixNsWrappedArray
 }
 
-// GetPrefixNsWrappedArrayOk returns a tuple with the PrefixNsWrappedArray field if it's non-nil, zero value otherwise
+// GetPrefixNsWrappedArrayOk returns a tuple with the PrefixNsWrappedArray field value if set, zero value otherwise
 // and a boolean to check if the value has been set.
 func (o *XmlItem) GetPrefixNsWrappedArrayOk() ([]int32, bool) {
 	if o == nil || o.PrefixNsWrappedArray == nil {
@@ -1030,98 +1004,26 @@ func (o *XmlItem) SetPrefixNsWrappedArray(v []int32) {
 	o.PrefixNsWrappedArray = &v
 }
 
+type NullableXmlItem struct {
+	Value XmlItem
+	ExplicitNull bool
+}
+
+func (v NullableXmlItem) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+		return json.Marshal(v.Value)
+	}	
+}
 
-// MarshalJSON returns the JSON representation of the model.
-func (o XmlItem) MarshalJSON() ([]byte, error) {
-	toSerialize := map[string]interface{}{}
-	if o.AttributeString != nil {
-		toSerialize["attribute_string"] = o.AttributeString
-	}
-	if o.AttributeNumber != nil {
-		toSerialize["attribute_number"] = o.AttributeNumber
-	}
-	if o.AttributeInteger != nil {
-		toSerialize["attribute_integer"] = o.AttributeInteger
-	}
-	if o.AttributeBoolean != nil {
-		toSerialize["attribute_boolean"] = o.AttributeBoolean
-	}
-	if o.WrappedArray != nil {
-		toSerialize["wrapped_array"] = o.WrappedArray
-	}
-	if o.NameString != nil {
-		toSerialize["name_string"] = o.NameString
-	}
-	if o.NameNumber != nil {
-		toSerialize["name_number"] = o.NameNumber
-	}
-	if o.NameInteger != nil {
-		toSerialize["name_integer"] = o.NameInteger
-	}
-	if o.NameBoolean != nil {
-		toSerialize["name_boolean"] = o.NameBoolean
-	}
-	if o.NameArray != nil {
-		toSerialize["name_array"] = o.NameArray
-	}
-	if o.NameWrappedArray != nil {
-		toSerialize["name_wrapped_array"] = o.NameWrappedArray
-	}
-	if o.PrefixString != nil {
-		toSerialize["prefix_string"] = o.PrefixString
-	}
-	if o.PrefixNumber != nil {
-		toSerialize["prefix_number"] = o.PrefixNumber
-	}
-	if o.PrefixInteger != nil {
-		toSerialize["prefix_integer"] = o.PrefixInteger
-	}
-	if o.PrefixBoolean != nil {
-		toSerialize["prefix_boolean"] = o.PrefixBoolean
+func (v *NullableXmlItem) UnmarshalJSON(src []byte) error {
+	if bytes.Equal(src, []byte("null")) {
+		v.ExplicitNull = true
+		return nil
 	}
-	if o.PrefixArray != nil {
-		toSerialize["prefix_array"] = o.PrefixArray
-	}
-	if o.PrefixWrappedArray != nil {
-		toSerialize["prefix_wrapped_array"] = o.PrefixWrappedArray
-	}
-	if o.NamespaceString != nil {
-		toSerialize["namespace_string"] = o.NamespaceString
-	}
-	if o.NamespaceNumber != nil {
-		toSerialize["namespace_number"] = o.NamespaceNumber
-	}
-	if o.NamespaceInteger != nil {
-		toSerialize["namespace_integer"] = o.NamespaceInteger
-	}
-	if o.NamespaceBoolean != nil {
-		toSerialize["namespace_boolean"] = o.NamespaceBoolean
-	}
-	if o.NamespaceArray != nil {
-		toSerialize["namespace_array"] = o.NamespaceArray
-	}
-	if o.NamespaceWrappedArray != nil {
-		toSerialize["namespace_wrapped_array"] = o.NamespaceWrappedArray
-	}
-	if o.PrefixNsString != nil {
-		toSerialize["prefix_ns_string"] = o.PrefixNsString
-	}
-	if o.PrefixNsNumber != nil {
-		toSerialize["prefix_ns_number"] = o.PrefixNsNumber
-	}
-	if o.PrefixNsInteger != nil {
-		toSerialize["prefix_ns_integer"] = o.PrefixNsInteger
-	}
-	if o.PrefixNsBoolean != nil {
-		toSerialize["prefix_ns_boolean"] = o.PrefixNsBoolean
-	}
-	if o.PrefixNsArray != nil {
-		toSerialize["prefix_ns_array"] = o.PrefixNsArray
-	}
-	if o.PrefixNsWrappedArray != nil {
-		toSerialize["prefix_ns_wrapped_array"] = o.PrefixNsWrappedArray
-	}
-	return json.Marshal(toSerialize)
-}
 
+	return json.Unmarshal(src, &v.Value)
+}
 
diff --git a/samples/client/petstore/go-experimental/go-petstore/utils.go b/samples/client/petstore/go-experimental/go-petstore/utils.go
index 8d2130be3f47..3a3303b24451 100644
--- a/samples/client/petstore/go-experimental/go-petstore/utils.go
+++ b/samples/client/petstore/go-experimental/go-petstore/utils.go
@@ -9,7 +9,14 @@
 
 package petstore
 
-import "time"
+import (
+    "bytes"
+    "encoding/json"
+    "errors"
+    "time"
+)
+
+var ErrInvalidNullable = errors.New("nullable cannot have non-zero Value and ExplicitNull simultaneously")
 
 // PtrBool is a helper routine that returns a pointer to given integer value.
 func PtrBool(v bool) *bool { return &v }
@@ -23,9 +30,6 @@ func PtrInt32(v int32) *int32 { return &v }
 // PtrInt64 is a helper routine that returns a pointer to given integer value.
 func PtrInt64(v int64) *int64 { return &v }
 
-// PtrFloat is a helper routine that returns a pointer to given float value.
-func PtrFloat(v float32) *float32 { return &v }
-
 // PtrFloat32 is a helper routine that returns a pointer to given float value.
 func PtrFloat32(v float32) *float32 { return &v }
 
@@ -36,4 +40,205 @@ func PtrFloat64(v float64) *float64 { return &v }
 func PtrString(v string) *string { return &v }
 
 // PtrTime is helper routine that returns a pointer to given Time value.
-func PtrTime(v time.Time) *time.Time { return &v }
\ No newline at end of file
+func PtrTime(v time.Time) *time.Time { return &v }
+
+type NullableBool struct {
+    Value bool
+    ExplicitNull bool
+}
+
+func (v NullableBool) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableBool) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableInt struct {
+    Value int
+    ExplicitNull bool
+}
+
+func (v NullableInt) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+
+func (v *NullableInt) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableInt32 struct {
+    Value int32
+    ExplicitNull bool
+}
+
+func (v NullableInt32) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableInt32) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableInt64 struct {
+    Value int64
+    ExplicitNull bool
+}
+
+func (v NullableInt64) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableInt64) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableFloat32 struct {
+    Value float32
+    ExplicitNull bool
+}
+
+func (v NullableFloat32) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0.0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableFloat32) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableFloat64 struct {
+    Value float64
+    ExplicitNull bool
+}
+
+func (v NullableFloat64) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != 0.0:
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableFloat64) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableString struct {
+    Value string
+    ExplicitNull bool
+}
+
+func (v NullableString) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && v.Value != "":
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return json.Marshal(v.Value)
+    }
+}
+
+func (v *NullableString) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
+
+type NullableTime struct {
+    Value time.Time
+    ExplicitNull bool
+}
+
+func (v NullableTime) MarshalJSON() ([]byte, error) {
+    switch {
+    case v.ExplicitNull && !v.Value.IsZero():
+        return nil, ErrInvalidNullable
+    case v.ExplicitNull:
+        return []byte("null"), nil
+    default:
+        return v.Value.MarshalJSON()
+    }
+}
+
+func (v *NullableTime) UnmarshalJSON(src []byte) error {
+    if bytes.Equal(src, []byte("null")) {
+        v.ExplicitNull = true
+        return nil
+    }
+
+    return json.Unmarshal(src, &v.Value)
+}
\ No newline at end of file
diff --git a/samples/client/petstore/go-experimental/pet_api_test.go b/samples/client/petstore/go-experimental/pet_api_test.go
index c1e8006bb0cf..847aa517af19 100644
--- a/samples/client/petstore/go-experimental/pet_api_test.go
+++ b/samples/client/petstore/go-experimental/pet_api_test.go
@@ -28,8 +28,8 @@ func TestMain(m *testing.M) {
 }
 
 func TestAddPet(t *testing.T) {
-	newPet := (sw.Pet{Id: sw.PtrInt64(12830), Name: sw.PtrString("gopher"),
-		PhotoUrls: &[]string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
+	newPet := (sw.Pet{Id: sw.PtrInt64(12830), Name: "gopher",
+		PhotoUrls: []string{"http://1.com", "http://2.com"}, Status: sw.PtrString("pending"),
 		Tags: &[]sw.Tag{sw.Tag{Id: sw.PtrInt64(1), Name: sw.PtrString("tag2")}}})
 
 	r, err := client.PetApi.AddPet(context.Background(), newPet)
@@ -286,7 +286,7 @@ func isPetCorrect(t *testing.T, id int64, name string, status string) {
 		t.Fatalf("Error while getting pet by id: %v", err)
 	} else {
 		assert.Equal(*resp.Id, int64(id), "Pet id should be equal")
-		assert.Equal(*resp.Name, name, fmt.Sprintf("Pet name should be %s", name))
+		assert.Equal(resp.Name, name, fmt.Sprintf("Pet name should be %s", name))
 		assert.Equal(*resp.Status, status, fmt.Sprintf("Pet status should be %s", status))
 
 		//t.Log(resp)
diff --git a/samples/client/petstore/go-experimental/user_api_test.go b/samples/client/petstore/go-experimental/user_api_test.go
index 07b82ebb9757..882608702097 100644
--- a/samples/client/petstore/go-experimental/user_api_test.go
+++ b/samples/client/petstore/go-experimental/user_api_test.go
@@ -14,7 +14,7 @@ func TestCreateUser(t *testing.T) {
 		Id:         sw.PtrInt64(1000),
 		FirstName:  sw.PtrString("gopher"),
 		LastName:   sw.PtrString("lang"),
-        Username:   sw.PtrString("gopher"),
+		Username:   sw.PtrString("gopher"),
 		Password:   sw.PtrString("lang"),
 		Email:      sw.PtrString("lang@test.com"),
 		Phone:      sw.PtrString("5101112222"),