diff --git a/modules/openapi-generator/src/main/resources/kotlin-spring/optionalDataType.mustache b/modules/openapi-generator/src/main/resources/kotlin-spring/optionalDataType.mustache
index 1a4578db7733..1e6ec005318d 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-spring/optionalDataType.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-spring/optionalDataType.mustache
@@ -1 +1 @@
-{{^isFile}}{{{dataType}}}{{^required}}{{^defaultValue}}?{{/defaultValue}}{{/required}}{{/isFile}}{{#isFile}}{{#isArray}}Array<{{/isArray}}org.springframework.web.multipart.MultipartFile{{#isArray}}>{{/isArray}}{{#isNullable}}?{{/isNullable}}{{/isFile}}
\ No newline at end of file
+{{^isFile}}{{{dataType}}}{{^required}}{{^defaultValue}}?{{/defaultValue}}{{/required}}{{/isFile}}{{#isFile}}{{#isArray}}Array<{{/isArray}}org.springframework.web.multipart.MultipartFile{{#isArray}}>{{/isArray}}{{^required}}?{{/required}}{{#required}}{{#isNullable}}?{{/isNullable}}{{/required}}{{/isFile}}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/spring/KotlinSpringServerCodegenTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/spring/KotlinSpringServerCodegenTest.java
index 4835aa65e8ec..da494789814c 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/spring/KotlinSpringServerCodegenTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/kotlin/spring/KotlinSpringServerCodegenTest.java
@@ -405,9 +405,9 @@ public void testNullableMultipartFile() throws IOException {
         assertFileContains(Paths.get(outputPath + "/src/main/kotlin/org/openapitools/api/NullableMultipartfileArrayApiController.kt"),
                 "files: Array<org.springframework.web.multipart.MultipartFile>?)");
         assertFileContains(Paths.get(outputPath + "/src/main/kotlin/org/openapitools/api/NonNullableMultipartfileApiController.kt"),
-                "file: org.springframework.web.multipart.MultipartFile)");
+                "file: org.springframework.web.multipart.MultipartFile?)");
         assertFileContains(Paths.get(outputPath + "/src/main/kotlin/org/openapitools/api/NonNullableMultipartfileArrayApiController.kt"),
-                "files: Array<org.springframework.web.multipart.MultipartFile>)");
+                "files: Array<org.springframework.web.multipart.MultipartFile>?)");
     }
 
     @Test
diff --git a/samples/server/petstore/kotlin-spring-cloud/src/main/kotlin/org/openapitools/api/PetApi.kt b/samples/server/petstore/kotlin-spring-cloud/src/main/kotlin/org/openapitools/api/PetApi.kt
index 88fdcb3bdd40..79e46ede1d5d 100644
--- a/samples/server/petstore/kotlin-spring-cloud/src/main/kotlin/org/openapitools/api/PetApi.kt
+++ b/samples/server/petstore/kotlin-spring-cloud/src/main/kotlin/org/openapitools/api/PetApi.kt
@@ -110,7 +110,7 @@ interface PetApi {
             produces = ["application/json"],
             consumes = ["multipart/form-data"]
     )
-    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
     }
 }
diff --git a/samples/server/petstore/kotlin-spring-default/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-spring-default/src/main/kotlin/org/openapitools/api/PetApiController.kt
index 4da69ab07131..3e4240107253 100644
--- a/samples/server/petstore/kotlin-spring-default/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-spring-default/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -176,7 +176,7 @@ class PetApiController() {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiController.kt
index da8c6b076bb5..cd920cd5bcda 100644
--- a/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -106,7 +106,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiService.kt
index 031da963d22d..54df94484e45 100644
--- a/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -99,5 +99,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index 6600f5535137..a81dbcbdb0a5 100644
--- a/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot-3/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -34,7 +34,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiController.kt
index da8c6b076bb5..cd920cd5bcda 100644
--- a/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -106,7 +106,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiService.kt
index 031da963d22d..54df94484e45 100644
--- a/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -99,5 +99,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index 6600f5535137..a81dbcbdb0a5 100644
--- a/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot-additionalproperties/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -34,7 +34,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-delegate-nodefaults/src/main/kotlin/org/openapitools/api/PetApi.kt b/samples/server/petstore/kotlin-springboot-delegate-nodefaults/src/main/kotlin/org/openapitools/api/PetApi.kt
index 792572559201..da2f9b1327fb 100644
--- a/samples/server/petstore/kotlin-springboot-delegate-nodefaults/src/main/kotlin/org/openapitools/api/PetApi.kt
+++ b/samples/server/petstore/kotlin-springboot-delegate-nodefaults/src/main/kotlin/org/openapitools/api/PetApi.kt
@@ -199,7 +199,7 @@ interface PetApi {
             produces = ["application/json"],
             consumes = ["multipart/form-data"]
     )
-    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return getDelegate().uploadFile(petId, additionalMetadata, file)
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-delegate-nodefaults/src/main/kotlin/org/openapitools/api/PetApiDelegate.kt b/samples/server/petstore/kotlin-springboot-delegate-nodefaults/src/main/kotlin/org/openapitools/api/PetApiDelegate.kt
index 706adc4ea385..fef8502227de 100644
--- a/samples/server/petstore/kotlin-springboot-delegate-nodefaults/src/main/kotlin/org/openapitools/api/PetApiDelegate.kt
+++ b/samples/server/petstore/kotlin-springboot-delegate-nodefaults/src/main/kotlin/org/openapitools/api/PetApiDelegate.kt
@@ -68,6 +68,6 @@ interface PetApiDelegate {
      */
     fun uploadFile(petId: kotlin.Long,
         additionalMetadata: kotlin.String?,
-        file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse>
+        file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse>
 
 }
diff --git a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApi.kt b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApi.kt
index 3816bc65b78b..5715749e0491 100644
--- a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApi.kt
+++ b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApi.kt
@@ -198,7 +198,7 @@ interface PetApi {
             produces = ["application/json"],
             consumes = ["multipart/form-data"]
     )
-    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return getDelegate().uploadFile(petId, additionalMetadata, file)
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApiDelegate.kt b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApiDelegate.kt
index 6169bf64c41c..231091206d9f 100644
--- a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApiDelegate.kt
+++ b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApiDelegate.kt
@@ -150,7 +150,7 @@ interface PetApiDelegate {
      */
     fun uploadFile(petId: kotlin.Long,
         additionalMetadata: kotlin.String?,
-        file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+        file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         getRequest().ifPresent { request ->
             for (mediaType in MediaType.parseMediaTypes(request.getHeader("Accept"))) {
                 if (mediaType.isCompatibleWith(MediaType.valueOf("application/json"))) {
diff --git a/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiController.kt
index d227b75281a7..84c4333e8944 100644
--- a/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -172,7 +172,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiService.kt
index db655b8a7978..bee779a69332 100644
--- a/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -90,5 +90,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index a48482be32bd..6b401e7ee880 100644
--- a/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot-modelMutable/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -34,7 +34,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiController.kt
index 26f2ad661da4..05575e31959f 100644
--- a/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -177,7 +177,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    suspend fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    suspend fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiService.kt
index ce1e55020fff..9a6c4b569f00 100644
--- a/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -100,5 +100,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    suspend fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    suspend fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index 751d8c0b477e..2590f434f52c 100644
--- a/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot-reactive-without-flow/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -35,7 +35,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override suspend fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override suspend fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiController.kt
index fff401053667..3a9a2760dd62 100644
--- a/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -177,7 +177,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    suspend fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    suspend fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiService.kt
index 2728966a96f4..29ff5bc85617 100644
--- a/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -100,5 +100,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    suspend fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    suspend fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index d1fce342257d..58b6df4cc091 100644
--- a/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot-reactive/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -35,7 +35,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override suspend fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override suspend fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-request-cookie/src/main/kotlin/org/openapitools/api/PetApi.kt b/samples/server/petstore/kotlin-springboot-request-cookie/src/main/kotlin/org/openapitools/api/PetApi.kt
index 565b6264e4d7..f51f80ddc62e 100644
--- a/samples/server/petstore/kotlin-springboot-request-cookie/src/main/kotlin/org/openapitools/api/PetApi.kt
+++ b/samples/server/petstore/kotlin-springboot-request-cookie/src/main/kotlin/org/openapitools/api/PetApi.kt
@@ -196,7 +196,7 @@ interface PetApi {
             produces = ["application/json"],
             consumes = ["multipart/form-data"]
     )
-    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiController.kt
index 9f46d6767fea..89a04feba590 100644
--- a/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -175,7 +175,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    fun uploadFile(@ApiParam(value = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@ApiParam(value = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@ApiParam(value = "file detail") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile(@ApiParam(value = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@ApiParam(value = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@ApiParam(value = "file detail") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiService.kt
index db655b8a7978..bee779a69332 100644
--- a/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -90,5 +90,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index a48482be32bd..6b401e7ee880 100644
--- a/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot-source-swagger1/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -34,7 +34,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiController.kt
index d227b75281a7..84c4333e8944 100644
--- a/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -172,7 +172,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile(@Parameter(description = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@Parameter(description = "file to upload") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiService.kt
index db655b8a7978..bee779a69332 100644
--- a/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -90,5 +90,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index a48482be32bd..6b401e7ee880 100644
--- a/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot-source-swagger2/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -34,7 +34,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiController.kt
index 9f46d6767fea..89a04feba590 100644
--- a/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -175,7 +175,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    fun uploadFile(@ApiParam(value = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@ApiParam(value = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@ApiParam(value = "file detail") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile(@ApiParam(value = "ID of pet to update", required = true) @PathVariable("petId") petId: kotlin.Long,@ApiParam(value = "Additional data to pass to server") @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? ,@ApiParam(value = "file detail") @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiService.kt b/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiService.kt
index db655b8a7978..bee779a69332 100644
--- a/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiService.kt
+++ b/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiService.kt
@@ -90,5 +90,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse
 }
diff --git a/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt b/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
index a48482be32bd..6b401e7ee880 100644
--- a/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
+++ b/samples/server/petstore/kotlin-springboot-springfox/src/main/kotlin/org/openapitools/api/PetApiServiceImpl.kt
@@ -34,7 +34,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }
diff --git a/samples/server/petstore/kotlin-springboot-x-kotlin-implements/src/main/kotlin/org/openapitools/api/PetApi.kt b/samples/server/petstore/kotlin-springboot-x-kotlin-implements/src/main/kotlin/org/openapitools/api/PetApi.kt
index e83175693b7c..e14a637b809b 100644
--- a/samples/server/petstore/kotlin-springboot-x-kotlin-implements/src/main/kotlin/org/openapitools/api/PetApi.kt
+++ b/samples/server/petstore/kotlin-springboot-x-kotlin-implements/src/main/kotlin/org/openapitools/api/PetApi.kt
@@ -95,5 +95,5 @@ interface PetApi {
             produces = ["application/json"],
             consumes = ["multipart/form-data"]
     )
-    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse>
+    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse>
 }
diff --git a/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiController.kt
index e704691f8020..4e393ceef9b1 100644
--- a/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -105,7 +105,7 @@ class PetApiController(@Autowired(required = true) val service: PetApiService) {
         produces = ["application/json"],
         consumes = ["multipart/form-data"]
     )
-    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile): ResponseEntity<ModelApiResponse> {
+    fun uploadFile( @PathVariable("petId") petId: kotlin.Long, @Valid @RequestParam(value = "additionalMetadata", required = false) additionalMetadata: kotlin.String? , @Valid @RequestPart("file", required = false) file: org.springframework.web.multipart.MultipartFile?): ResponseEntity<ModelApiResponse> {
         return ResponseEntity(service.uploadFile(petId, additionalMetadata, file), HttpStatus.valueOf(200))
     }
 }
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 db655b8a7978..bee779a69332 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
@@ -90,5 +90,5 @@ interface PetApiService {
      * @return successful operation (status code 200)
      * @see PetApi#uploadFile
      */
-    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse
+    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): 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 a48482be32bd..6b401e7ee880 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
@@ -34,7 +34,7 @@ class PetApiServiceImpl : PetApiService {
         TODO("Implement me")
     }
 
-    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile): ModelApiResponse {
+    override fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: org.springframework.web.multipart.MultipartFile?): ModelApiResponse {
         TODO("Implement me")
     }
 }