diff --git a/bin/utils/ensure-up-to-date b/bin/utils/ensure-up-to-date
index d950ce71e808..41dc4b9cd1a1 100755
--- a/bin/utils/ensure-up-to-date
+++ b/bin/utils/ensure-up-to-date
@@ -24,6 +24,7 @@ declare -a scripts=(
 "./bin/kotlin-client-string.sh"
 "./bin/kotlin-client-threetenbp.sh"
 "./bin/kotlin-server-petstore.sh"
+"./bin/kotlin-springboot-petstore-server.sh"
 "./bin/mysql-schema-petstore.sh"
 "./bin/python-petstore-all.sh"
 "./bin/openapi3/python-petstore.sh"
diff --git a/modules/openapi-generator/src/main/resources/kotlin-spring/service.mustache b/modules/openapi-generator/src/main/resources/kotlin-spring/service.mustache
index 37892a1f5347..3da1b1a61b04 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-spring/service.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-spring/service.mustache
@@ -7,7 +7,7 @@ package {{package}}
 interface {{classname}}Service {
 {{#operation}}
 
-    fun {{operationId}}({{#allParams}}{{paramName}}: {{{dataType}}}{{#hasMore}},{{/hasMore}}{{/allParams}}): {{>returnTypes}}
+    fun {{operationId}}({{#allParams}}{{paramName}}: {{{dataType}}}{{^required}}?{{/required}}{{#hasMore}},{{/hasMore}}{{/allParams}}): {{>returnTypes}}
 {{/operation}}
 }
 {{/operations}}
diff --git a/modules/openapi-generator/src/main/resources/kotlin-spring/serviceImpl.mustache b/modules/openapi-generator/src/main/resources/kotlin-spring/serviceImpl.mustache
index 134600ecfc09..23944a9dde32 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-spring/serviceImpl.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-spring/serviceImpl.mustache
@@ -8,7 +8,7 @@ import org.springframework.stereotype.Service
 class {{classname}}ServiceImpl : {{classname}}Service {
 {{#operation}}
 
-    override fun {{operationId}}({{#allParams}}{{paramName}}: {{{dataType}}}{{#hasMore}},{{/hasMore}}{{/allParams}}): {{>returnTypes}} {
+    override fun {{operationId}}({{#allParams}}{{paramName}}: {{{dataType}}}{{^required}}?{{/required}}{{#hasMore}},{{/hasMore}}{{/allParams}}): {{>returnTypes}} {
         TODO("Implement me")
     }
 {{/operation}}
diff --git a/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiService.kt
index 5218a25b638a..ae9348716a1c 100644
--- a/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -7,7 +7,7 @@ interface PetApiService {
 
     fun addPet(body: Pet): Unit
 
-    fun deletePet(petId: Long,apiKey: String): Unit
+    fun deletePet(petId: Long,apiKey: String?): Unit
 
     fun findPetsByStatus(status: List<String>): List<Pet>
 
@@ -17,7 +17,7 @@ interface PetApiService {
 
     fun updatePet(body: Pet): Unit
 
-    fun updatePetWithForm(petId: Long,name: String,status: String): Unit
+    fun updatePetWithForm(petId: Long,name: String?,status: String?): Unit
 
-    fun uploadFile(petId: Long,additionalMetadata: String,file: org.springframework.core.io.Resource): ModelApiResponse
+    fun uploadFile(petId: Long,additionalMetadata: String?,file: org.springframework.core.io.Resource?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index 8de49b91daa5..1c2bad4d65fe 100644
--- a/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -10,7 +10,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun deletePet(petId: Long,apiKey: String): Unit {
+    override fun deletePet(petId: Long,apiKey: String?): Unit {
         TODO("Implement me")
     }
 
@@ -30,11 +30,11 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun updatePetWithForm(petId: Long,name: String,status: String): Unit {
+    override fun updatePetWithForm(petId: Long,name: String?,status: String?): Unit {
         TODO("Implement me")
     }
 
-    override fun uploadFile(petId: Long,additionalMetadata: String,file: org.springframework.core.io.Resource): ModelApiResponse {
+    override fun uploadFile(petId: Long,additionalMetadata: String?,file: org.springframework.core.io.Resource?): ModelApiResponse {
         TODO("Implement me")
     }
 }