[Java] Fix content for enum in MultiPart (#21428)

* [Java] Fix content for enum in addPartToMultiPartBuilder ([#19973](https://github.com/OpenAPITools/openapi-generator/issues/19973))

* [Java] Fix content for enum with restclient (#19973)

* [Java] Fix content for enum with restclient (#19973)

* [Java] Fix content for enum with restclient (#19973)

* update samples

---------

Co-authored-by: Michael Bornholdt Nielsen <michaelbornholdtnielsen@gmail.com>
Co-authored-by: Michael Bornholdt Nielsen <jarryDk@users.noreply.github.com>

.github/workflows/samples-java-client-jdk17.yaml

@@ -7,12 +7,14 @@ on:
       - samples/client/petstore/java/webclient-jakarta/**
       - samples/client/petstore/java/restclient-*/**
       - samples/client/petstore/java/webclient-useSingleRequestParameter/**
+      - samples/client/others/java/restclient-enum-in-multipart/**
   pull_request:
     paths:
       - samples/client/petstore/java/resttemplate-jakarta/**
       - samples/client/petstore/java/webclient-jakarta/**
       - samples/client/petstore/java/restclient-*/**
       - samples/client/petstore/java/webclient-useSingleRequestParameter/**
+      - samples/client/others/java/restclient-enum-in-multipart/**
 jobs:
   build:
     name: Build Java Client JDK17
@@ -30,6 +32,7 @@ jobs:
           - samples/client/petstore/java/restclient-useSingleRequestParameter
           - samples/client/petstore/java/restclient-useSingleRequestParameter-static
           - samples/client/petstore/java/webclient-useSingleRequestParameter
+          - samples/client/others/java/restclient-enum-in-multipart
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-java@v4

bin/configs/java-restclient-enum-in-multipart.yaml

@@ -0,0 +1,7 @@
+generatorName: java
+outputDir: samples/client/others/java/restclient-enum-in-multipart
+library: restclient
+inputSpec: modules/openapi-generator/src/test/resources/3_1/enum-in-multipart.yaml
+templateDir: modules/openapi-generator/src/main/resources/Java
+additionalProperties:
+  hideGenerationTimestamp: "true"

modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache

@@ -685,6 +685,18 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         addCookiesToRequest(cookieParams, requestBuilder);
         addCookiesToRequest(defaultCookies, requestBuilder);
 
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
         var selectedBody = selectBody(body, formParams, contentType);
         if (selectedBody != null) {
           requestBuilder.body(selectedBody);

modules/openapi-generator/src/test/resources/3_1/enum-in-multipart.yaml

@@ -0,0 +1,105 @@
+openapi: 3.1.0
+info:
+  description: API
+  title: API
+  version: 1.0.0
+servers:
+- description: "Localhost, used when testing"
+  url: http://localhost:8080
+security:
+- basicAuth: []
+paths:
+  /messages:
+    post:
+      description: Creates a new message
+      x-content-type: multipart/form-data
+      x-accepts:
+      - application/json
+      operationId: CreateMessage
+      requestBody:
+        $ref: "#/components/requestBodies/CreateMessageBody"
+      responses:
+        "201":
+          $ref: "#/components/responses/MessageCreatedResponse"
+      summary: Creates a new message
+      tags:
+      - BAS
+components:
+  parameters:
+    messageId:
+      description: The identifier the message
+      explode: false
+      in: path
+      name: messageId
+      required: true
+      schema:
+        format: uuid
+        type: string
+      style: simple
+  requestBodies:
+    CreateMessageBody:
+      content:
+        multipart/form-data:
+          schema:
+            $ref: "#/components/schemas/CreateMessage_request"
+      required: true
+  responses:
+    MessageCreatedResponse:
+      content:
+        application/json:
+          schema:
+            $ref: "#/components/schemas/inline_object"
+      description: The message was created.
+  schemas:
+    DataDirection:
+      description: The direction a message travels
+      enum:
+      - INGOING
+      - OUTGOING
+      type: string
+    DataChannel:
+      description: The transport-channel
+      enum:
+      - BIKE
+      - CAR
+      - BUS
+      - PLANE
+      type: string
+    messageId:
+      description: The messageID
+      format: uuid
+      type: string
+    CreateMessage_request:
+      properties:
+        fileContent:
+          description: The message payload
+          format: binary
+          type: string
+        idempotencyKey:
+          type: string
+        dataDirection:
+          $ref: "#/components/schemas/DataDirection"
+        dataChannel:
+          $ref: "#/components/schemas/DataChannel"
+      required:
+      - dataChannel
+      - dataDirection
+      - fileContent
+      - fileType
+      - idempotencyKey
+      type: object
+    inline_object:
+      example:
+        messageId: 046b6c7f-0b8a-43b9-b35d-6489e6daee91
+      properties:
+        messageId:
+          description: The messageID
+          format: uuid
+          type: string
+      required:
+      - messageId
+  securitySchemes:
+    basicAuth:
+      scheme: basic
+      type: http
+

samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ApiClient.java

@@ -639,6 +639,18 @@ public class ApiClient extends JavaTimeFormatter {
         addCookiesToRequest(cookieParams, requestBuilder);
         addCookiesToRequest(defaultCookies, requestBuilder);
 
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
         var selectedBody = selectBody(body, formParams, contentType);
         if (selectedBody != null) {
           requestBuilder.body(selectedBody);

samples/client/others/java/restclient-enum-in-multipart/.github/workflows/maven.yml

@@ -0,0 +1,30 @@
+# This workflow will build a Java project with Maven, and cache/restore any dependencies to improve the workflow execution time
+# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
+#
+# This file is auto-generated by OpenAPI Generator (https://openapi-generator.tech)
+
+name: Java CI with Maven
+
+on:
+  push:
+    branches: [ main, master ]
+  pull_request:
+    branches: [ main, master ]
+
+jobs:
+  build:
+    name: Build API
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        java: [ 17, 21 ]
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up JDK
+      uses: actions/setup-java@v4
+      with:
+        java-version: ${{ matrix.java }}
+        distribution: 'temurin'
+        cache: maven
+    - name: Build with Maven
+      run: mvn -B package --no-transfer-progress --file pom.xml

samples/client/others/java/restclient-enum-in-multipart/.gitignore

@@ -0,0 +1,21 @@
+*.class
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.ear
+
+# exclude jar for gradle wrapper
+!gradle/wrapper/*.jar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+
+# build files
+**/target
+target
+.gradle
+build

samples/client/others/java/restclient-enum-in-multipart/.openapi-generator-ignore

@@ -0,0 +1,23 @@
+# OpenAPI Generator Ignore
+# Generated by openapi-generator https://github.com/openapitools/openapi-generator
+
+# Use this file to prevent files from being overwritten by the generator.
+# The patterns follow closely to .gitignore or .dockerignore.
+
+# As an example, the C# client generator defines ApiClient.cs.
+# You can make changes and tell OpenAPI Generator to ignore just this file by uncommenting the following line:
+#ApiClient.cs
+
+# You can match any string of characters against a directory, file or extension with a single asterisk (*):
+#foo/*/qux
+# The above matches foo/bar/qux and foo/baz/qux, but not foo/bar/baz/qux
+
+# You can recursively match patterns against a directory, file or extension with a double asterisk (**):
+#foo/**/qux
+# This matches foo/bar/qux, foo/baz/qux, and foo/bar/baz/qux
+
+# You can also negate patterns with an exclamation (!).
+# For example, you can ignore all files in a docs folder with the file extension .md:
+#docs/*.md
+# Then explicitly reverse the ignore rule for a single file:
+#!docs/README.md

samples/client/others/java/restclient-enum-in-multipart/.openapi-generator/FILES

@@ -0,0 +1,36 @@
+.github/workflows/maven.yml
+.gitignore
+.travis.yml
+README.md
+api/openapi.yaml
+build.gradle
+build.sbt
+docs/BasApi.md
+docs/DataChannel.md
+docs/DataDirection.md
+docs/InlineObject.md
+git_push.sh
+gradle.properties
+gradle/wrapper/gradle-wrapper.jar
+gradle/wrapper/gradle-wrapper.properties
+gradlew
+gradlew.bat
+pom.xml
+settings.gradle
+src/main/AndroidManifest.xml
+src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/JavaTimeFormatter.java
+src/main/java/org/openapitools/client/RFC3339DateFormat.java
+src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
+src/main/java/org/openapitools/client/RFC3339JavaTimeModule.java
+src/main/java/org/openapitools/client/ServerConfiguration.java
+src/main/java/org/openapitools/client/ServerVariable.java
+src/main/java/org/openapitools/client/StringUtil.java
+src/main/java/org/openapitools/client/api/BasApi.java
+src/main/java/org/openapitools/client/auth/ApiKeyAuth.java
+src/main/java/org/openapitools/client/auth/Authentication.java
+src/main/java/org/openapitools/client/auth/HttpBasicAuth.java
+src/main/java/org/openapitools/client/auth/HttpBearerAuth.java
+src/main/java/org/openapitools/client/model/DataChannel.java
+src/main/java/org/openapitools/client/model/DataDirection.java
+src/main/java/org/openapitools/client/model/InlineObject.java

samples/client/others/java/restclient-enum-in-multipart/.openapi-generator/VERSION

@@ -0,0 +1 @@
+7.14.0-SNAPSHOT

samples/client/others/java/restclient-enum-in-multipart/.travis.yml

@@ -0,0 +1,22 @@
+#
+# Generated by OpenAPI Generator: https://openapi-generator.tech
+#
+# Ref: https://docs.travis-ci.com/user/languages/java/
+#
+language: java
+jdk:
+  - openjdk12
+  - openjdk11
+  - openjdk10
+  - openjdk9
+  - openjdk8
+before_install:
+  # ensure gradlew has proper permission
+  - chmod a+x ./gradlew
+script:
+  # test using maven
+  #- mvn test
+  # test using gradle
+  - gradle test
+  # test using sbt
+  # - sbt test

samples/client/others/java/restclient-enum-in-multipart/README.md

@@ -0,0 +1,155 @@
+# openapi-java-client
+
+API
+
+- API version: 1.0.0
+
+- Generator version: 7.14.0-SNAPSHOT
+
+API
+
+
+*Automatically generated by the [OpenAPI Generator](https://openapi-generator.tech)*
+
+## Requirements
+
+Building the API client library requires:
+
+1. Java 17+
+2. Maven/Gradle
+
+## Installation
+
+To install the API client library to your local Maven repository, simply execute:
+
+```shell
+mvn clean install
+```
+
+To deploy it to a remote Maven repository instead, configure the settings of the repository and execute:
+
+```shell
+mvn clean deploy
+```
+
+Refer to the [OSSRH Guide](http://central.sonatype.org/pages/ossrh-guide.html) for more information.
+
+### Maven users
+
+Add this dependency to your project's POM:
+
+```xml
+<dependency>
+  <groupId>org.openapitools</groupId>
+  <artifactId>openapi-java-client</artifactId>
+  <version>1.0.0</version>
+  <scope>compile</scope>
+</dependency>
+```
+
+### Gradle users
+
+Add this dependency to your project's build file:
+
+```groovy
+  repositories {
+    mavenCentral()     // Needed if the 'openapi-java-client' jar has been published to maven central.
+    mavenLocal()       // Needed if the 'openapi-java-client' jar has been published to the local maven repo.
+  }
+
+  dependencies {
+     implementation "org.openapitools:openapi-java-client:1.0.0"
+  }
+```
+
+### Others
+
+At first generate the JAR by executing:
+
+```shell
+mvn clean package
+```
+
+Then manually install the following JARs:
+
+- `target/openapi-java-client-1.0.0.jar`
+- `target/lib/*.jar`
+
+## Getting Started
+
+Please follow the [installation](#installation) instruction and execute the following Java code:
+
+```java
+
+import org.openapitools.client.*;
+import org.openapitools.client.auth.*;
+import org.openapitools.client.model.*;
+import org.openapitools.client.api.BasApi;
+
+public class BasApiExample {
+
+    public static void main(String[] args) {
+        ApiClient defaultClient = new ApiClient();
+        defaultClient.setBasePath("http://localhost:8080");
+        
+        // Configure HTTP basic authorization: basicAuth
+        HttpBasicAuth basicAuth = (HttpBasicAuth) defaultClient.getAuthentication("basicAuth");
+        basicAuth.setUsername("YOUR USERNAME");
+        basicAuth.setPassword("YOUR PASSWORD");
+
+        BasApi apiInstance = new BasApi(defaultClient);
+        File fileContent = new File("/path/to/file"); // File | The message payload
+        String idempotencyKey = "idempotencyKey_example"; // String | 
+        DataDirection dataDirection = DataDirection.fromValue("INGOING"); // DataDirection | 
+        DataChannel dataChannel = DataChannel.fromValue("BIKE"); // DataChannel | 
+        try {
+            InlineObject result = apiInstance.createMessage(fileContent, idempotencyKey, dataDirection, dataChannel);
+            System.out.println(result);
+        } catch (HttpStatusCodeException e) {
+            System.err.println("Exception when calling BasApi#createMessage");
+            System.err.println("Status code: " + e.getStatusCode().value());
+            System.err.println("Reason: " + e.getResponseBodyAsString());
+            System.err.println("Response headers: " + e.getResponseHeaders());
+            e.printStackTrace();
+        }
+    }
+}
+
+```
+
+## Documentation for API Endpoints
+
+All URIs are relative to *http://localhost:8080*
+
+Class | Method | HTTP request | Description
+------------ | ------------- | ------------- | -------------
+*BasApi* | [**createMessage**](docs/BasApi.md#createMessage) | **POST** /messages | Creates a new message
+
+
+## Documentation for Models
+
+ - [DataChannel](docs/DataChannel.md)
+ - [DataDirection](docs/DataDirection.md)
+ - [InlineObject](docs/InlineObject.md)
+
+
+<a id="documentation-for-authorization"></a>
+## Documentation for Authorization
+
+
+Authentication schemes defined for the API:
+<a id="basicAuth"></a>
+### basicAuth
+
+
+- **Type**: HTTP basic authentication
+
+
+## Recommendation
+
+It's recommended to create an instance of `ApiClient` per thread in a multithreaded environment to avoid any potential issues.
+
+## Author
+
+
+

samples/client/others/java/restclient-enum-in-multipart/api/openapi.yaml

@@ -0,0 +1,102 @@
+openapi: 3.1.0
+info:
+  description: API
+  title: API
+  version: 1.0.0
+servers:
+- description: "Localhost, used when testing"
+  url: http://localhost:8080
+security:
+- basicAuth: []
+paths:
+  /messages:
+    post:
+      description: Creates a new message
+      operationId: CreateMessage
+      requestBody:
+        $ref: "#/components/requestBodies/CreateMessageBody"
+      responses:
+        "201":
+          $ref: "#/components/responses/MessageCreatedResponse"
+      summary: Creates a new message
+      tags:
+      - BAS
+      x-content-type: multipart/form-data
+      x-accepts:
+      - application/json
+components:
+  parameters:
+    messageId:
+      description: The identifier the message
+      explode: false
+      in: path
+      name: messageId
+      required: true
+      schema:
+        format: uuid
+      style: simple
+  requestBodies:
+    CreateMessageBody:
+      content:
+        multipart/form-data:
+          schema:
+            $ref: "#/components/schemas/CreateMessage_request"
+      required: true
+  responses:
+    MessageCreatedResponse:
+      content:
+        application/json:
+          schema:
+            $ref: "#/components/schemas/inline_object"
+      description: The message was created.
+  schemas:
+    DataDirection:
+      description: The direction a message travels
+      enum:
+      - INGOING
+      - OUTGOING
+      type: string
+    DataChannel:
+      description: The transport-channel
+      enum:
+      - BIKE
+      - CAR
+      - BUS
+      - PLANE
+      type: string
+    messageId:
+      description: The messageID
+      format: uuid
+      type: string
+    CreateMessage_request:
+      properties:
+        fileContent:
+          description: The message payload
+          format: binary
+          type: string
+        idempotencyKey:
+          type: string
+        dataDirection:
+          $ref: "#/components/schemas/DataDirection"
+        dataChannel:
+          $ref: "#/components/schemas/DataChannel"
+      required:
+      - dataChannel
+      - dataDirection
+      - fileContent
+      - idempotencyKey
+    inline_object:
+      example:
+        messageId: 046b6c7f-0b8a-43b9-b35d-6489e6daee91
+      properties:
+        messageId:
+          description: The messageID
+          format: uuid
+          type: string
+      required:
+      - messageId
+  securitySchemes:
+    basicAuth:
+      scheme: basic
+      type: http
+

samples/client/others/java/restclient-enum-in-multipart/build.gradle

@@ -0,0 +1,136 @@
+apply plugin: 'idea'
+apply plugin: 'eclipse'
+
+group = 'org.openapitools'
+version = '1.0.0'
+
+buildscript {
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+        classpath 'com.android.tools.build:gradle:1.5.+'
+        classpath 'com.github.dcendents:android-maven-gradle-plugin:1.3'
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+
+if(hasProperty('target') && target == 'android') {
+
+    apply plugin: 'com.android.library'
+    apply plugin: 'com.github.dcendents.android-maven'
+
+    android {
+        compileSdkVersion 23
+        buildToolsVersion '23.0.2'
+        defaultConfig {
+            minSdkVersion 14
+            targetSdkVersion 22
+        }
+        compileOptions {
+            sourceCompatibility JavaVersion.VERSION_17
+            targetCompatibility JavaVersion.VERSION_17
+        }
+
+        // Rename the aar correctly
+        libraryVariants.all { variant ->
+            variant.outputs.each { output ->
+                def outputFile = output.outputFile
+                if (outputFile != null && outputFile.name.endsWith('.aar')) {
+                    def fileName = "${project.name}-${variant.baseName}-${version}.aar"
+                    output.outputFile = new File(outputFile.parent, fileName)
+                }
+            }
+        }
+
+        dependencies {
+            provided "jakarta.annotation:jakarta.annotation-api:$jakarta_annotation_version"
+        }
+    }
+
+    afterEvaluate {
+        android.libraryVariants.all { variant ->
+            def task = project.tasks.create "jar${variant.name.capitalize()}", Jar
+            task.description = "Create jar artifact for ${variant.name}"
+            task.dependsOn variant.javaCompile
+            task.from variant.javaCompile.destinationDirectory
+            task.destinationDirectory = project.file("${project.buildDir}/outputs/jar")
+            task.archiveFileName = "${project.name}-${variant.baseName}-${version}.jar"
+            artifacts.add('archives', task);
+        }
+    }
+
+    task sourcesJar(type: Jar) {
+        from android.sourceSets.main.java.srcDirs
+        archiveClassifier = 'sources'
+    }
+
+    artifacts {
+        archives sourcesJar
+    }
+
+} else {
+
+    apply plugin: 'java'
+    apply plugin: 'maven-publish'
+
+    sourceCompatibility = JavaVersion.VERSION_17
+    targetCompatibility = JavaVersion.VERSION_17
+
+    publishing {
+        publications {
+            maven(MavenPublication) {
+               artifactId = 'openapi-java-client'
+               from components.java
+            }
+        }
+    }
+
+    task execute(type:JavaExec) {
+       mainClass = System.getProperty('mainClass')
+       classpath = sourceSets.main.runtimeClasspath
+    }
+}
+
+ext {
+    jackson_version = "2.17.1"
+    jackson_databind_version = "2.17.1"
+    jackson_databind_nullable_version = "0.2.6"
+    spring_web_version = "6.1.6"
+    jakarta_annotation_version = "2.1.1"
+    jodatime_version = "2.9.9"
+    junit_version = "5.10.2"
+}
+
+dependencies {
+    implementation "com.google.code.findbugs:jsr305:3.0.2"
+    implementation "org.springframework:spring-web:$spring_web_version"
+    implementation "org.springframework:spring-context:$spring_web_version"
+    implementation "com.fasterxml.jackson.core:jackson-core:$jackson_version"
+    implementation "com.fasterxml.jackson.core:jackson-annotations:$jackson_version"
+    implementation "com.fasterxml.jackson.core:jackson-databind:$jackson_databind_version"
+    implementation "com.fasterxml.jackson.jaxrs:jackson-jaxrs-json-provider:$jackson_version"
+    implementation "org.openapitools:jackson-databind-nullable:$jackson_databind_nullable_version"
+    implementation "com.fasterxml.jackson.datatype:jackson-datatype-jsr310:$jackson_version"
+    implementation "jakarta.annotation:jakarta.annotation-api:$jakarta_annotation_version"
+    testImplementation "org.junit.jupiter:junit-jupiter-api:$junit_version"
+    testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:$junit_version"
+}
+
+test {
+    // Enable JUnit 5 (Gradle 4.6+).
+    useJUnitPlatform()
+
+    // Always run tests, even when nothing changed.
+    dependsOn 'cleanTest'
+
+    // Show test results.
+    testLogging {
+        events "passed", "skipped", "failed"
+    }
+
+}

samples/client/others/java/restclient-enum-in-multipart/build.sbt

@@ -0,0 +1 @@
+# TODO

samples/client/others/java/restclient-enum-in-multipart/docs/BasApi.md

@@ -0,0 +1,87 @@
+# BasApi
+
+All URIs are relative to *http://localhost:8080*
+
+| Method | HTTP request | Description |
+|------------- | ------------- | -------------|
+| [**createMessage**](BasApi.md#createMessage) | **POST** /messages | Creates a new message |
+
+
+
+## createMessage
+
+> InlineObject createMessage(fileContent, idempotencyKey, dataDirection, dataChannel)
+
+Creates a new message
+
+Creates a new message
+
+### Example
+
+```java
+// Import classes:
+import org.openapitools.client.ApiClient;
+import org.openapitools.client.ApiException;
+import org.openapitools.client.Configuration;
+import org.openapitools.client.auth.*;
+import org.openapitools.client.models.*;
+import org.openapitools.client.api.BasApi;
+
+public class Example {
+    public static void main(String[] args) {
+        ApiClient defaultClient = Configuration.getDefaultApiClient();
+        defaultClient.setBasePath("http://localhost:8080");
+        
+        // Configure HTTP basic authorization: basicAuth
+        HttpBasicAuth basicAuth = (HttpBasicAuth) defaultClient.getAuthentication("basicAuth");
+        basicAuth.setUsername("YOUR USERNAME");
+        basicAuth.setPassword("YOUR PASSWORD");
+
+        BasApi apiInstance = new BasApi(defaultClient);
+        File fileContent = new File("/path/to/file"); // File | The message payload
+        String idempotencyKey = "idempotencyKey_example"; // String | 
+        DataDirection dataDirection = DataDirection.fromValue("INGOING"); // DataDirection | 
+        DataChannel dataChannel = DataChannel.fromValue("BIKE"); // DataChannel | 
+        try {
+            InlineObject result = apiInstance.createMessage(fileContent, idempotencyKey, dataDirection, dataChannel);
+            System.out.println(result);
+        } catch (ApiException e) {
+            System.err.println("Exception when calling BasApi#createMessage");
+            System.err.println("Status code: " + e.getCode());
+            System.err.println("Reason: " + e.getResponseBody());
+            System.err.println("Response headers: " + e.getResponseHeaders());
+            e.printStackTrace();
+        }
+    }
+}
+```
+
+### Parameters
+
+
+| Name | Type | Description  | Notes |
+|------------- | ------------- | ------------- | -------------|
+| **fileContent** | **File**| The message payload | |
+| **idempotencyKey** | **String**|  | |
+| **dataDirection** | [**DataDirection**](DataDirection.md)|  | [enum: INGOING, OUTGOING] |
+| **dataChannel** | [**DataChannel**](DataChannel.md)|  | [enum: BIKE, CAR, BUS, PLANE] |
+
+### Return type
+
+[**InlineObject**](InlineObject.md)
+
+### Authorization
+
+[basicAuth](../README.md#basicAuth)
+
+### HTTP request headers
+
+- **Content-Type**: multipart/form-data
+- **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **201** | The message was created. |  -  |
+

samples/client/others/java/restclient-enum-in-multipart/docs/DataChannel.md

@@ -0,0 +1,17 @@
+
+
+# DataChannel
+
+## Enum
+
+
+* `BIKE` (value: `"BIKE"`)
+
+* `CAR` (value: `"CAR"`)
+
+* `BUS` (value: `"BUS"`)
+
+* `PLANE` (value: `"PLANE"`)
+
+
+

samples/client/others/java/restclient-enum-in-multipart/docs/DataDirection.md

@@ -0,0 +1,13 @@
+
+
+# DataDirection
+
+## Enum
+
+
+* `INGOING` (value: `"INGOING"`)
+
+* `OUTGOING` (value: `"OUTGOING"`)
+
+
+

samples/client/others/java/restclient-enum-in-multipart/docs/InlineObject.md

@@ -0,0 +1,13 @@
+
+
+# InlineObject
+
+
+## Properties
+
+| Name | Type | Description | Notes |
+|------------ | ------------- | ------------- | -------------|
+|**messageId** | **UUID** | The messageID |  |
+
+
+

samples/client/others/java/restclient-enum-in-multipart/git_push.sh

@@ -0,0 +1,57 @@
+#!/bin/sh
+# ref: https://help.github.com/articles/adding-an-existing-project-to-github-using-the-command-line/
+#
+# Usage example: /bin/sh ./git_push.sh wing328 openapi-petstore-perl "minor update" "gitlab.com"
+
+git_user_id=$1
+git_repo_id=$2
+release_note=$3
+git_host=$4
+
+if [ "$git_host" = "" ]; then
+    git_host="github.com"
+    echo "[INFO] No command line input provided. Set \$git_host to $git_host"
+fi
+
+if [ "$git_user_id" = "" ]; then
+    git_user_id="GIT_USER_ID"
+    echo "[INFO] No command line input provided. Set \$git_user_id to $git_user_id"
+fi
+
+if [ "$git_repo_id" = "" ]; then
+    git_repo_id="GIT_REPO_ID"
+    echo "[INFO] No command line input provided. Set \$git_repo_id to $git_repo_id"
+fi
+
+if [ "$release_note" = "" ]; then
+    release_note="Minor update"
+    echo "[INFO] No command line input provided. Set \$release_note to $release_note"
+fi
+
+# Initialize the local directory as a Git repository
+git init
+
+# Adds the files in the local repository and stages them for commit.
+git add .
+
+# Commits the tracked changes and prepares them to be pushed to a remote repository.
+git commit -m "$release_note"
+
+# Sets the new remote
+git_remote=$(git remote)
+if [ "$git_remote" = "" ]; then # git remote not defined
+
+    if [ "$GIT_TOKEN" = "" ]; then
+        echo "[INFO] \$GIT_TOKEN (environment variable) is not set. Using the git credential in your environment."
+        git remote add origin https://${git_host}/${git_user_id}/${git_repo_id}.git
+    else
+        git remote add origin https://${git_user_id}:"${GIT_TOKEN}"@${git_host}/${git_user_id}/${git_repo_id}.git
+    fi
+
+fi
+
+git pull origin master
+
+# Pushes (Forces) the changes in the local repository up to the remote repository
+echo "Git pushing to https://${git_host}/${git_user_id}/${git_repo_id}.git"
+git push origin master 2>&1 | grep -v 'To https'

samples/client/others/java/restclient-enum-in-multipart/gradle.properties

@@ -0,0 +1,6 @@
+# This file is automatically generated by OpenAPI Generator (https://github.com/openAPITools/openapi-generator).
+# To include other gradle properties as part of the code generation process, please use the `gradleProperties` option.
+#
+# Gradle properties reference: https://docs.gradle.org/current/userguide/build_environment.html#sec:gradle_configuration_properties
+# For example, uncomment below to build for Android
+#target = android

samples/client/others/java/restclient-enum-in-multipart/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.7-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

samples/client/others/java/restclient-enum-in-multipart/gradlew

@@ -0,0 +1,249 @@
+#!/bin/sh
+
+#
+# Copyright © 2015-2021 the original authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+##############################################################################
+#
+#   Gradle start up script for POSIX generated by Gradle.
+#
+#   Important for running:
+#
+#   (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is
+#       noncompliant, but you have some other compliant shell such as ksh or
+#       bash, then to run this script, type that shell name before the whole
+#       command line, like:
+#
+#           ksh Gradle
+#
+#       Busybox and similar reduced shells will NOT work, because this script
+#       requires all of these POSIX shell features:
+#         * functions;
+#         * expansions «$var», «${var}», «${var:-default}», «${var+SET}»,
+#           «${var#prefix}», «${var%suffix}», and «$( cmd )»;
+#         * compound commands having a testable exit status, especially «case»;
+#         * various built-in commands including «command», «set», and «ulimit».
+#
+#   Important for patching:
+#
+#   (2) This script targets any POSIX shell, so it avoids extensions provided
+#       by Bash, Ksh, etc; in particular arrays are avoided.
+#
+#       The "traditional" practice of packing multiple parameters into a
+#       space-separated string is a well documented source of bugs and security
+#       problems, so this is (mostly) avoided, by progressively accumulating
+#       options in "$@", and eventually passing that to Java.
+#
+#       Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS,
+#       and GRADLE_OPTS) rely on word-splitting, this is performed explicitly;
+#       see the in-line comments for details.
+#
+#       There are tweaks for specific operating systems such as AIX, CygWin,
+#       Darwin, MinGW, and NonStop.
+#
+#   (3) This script is generated from the Groovy template
+#       https://github.com/gradle/gradle/blob/HEAD/subprojects/plugins/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt
+#       within the Gradle project.
+#
+#       You can find Gradle at https://github.com/gradle/gradle/.
+#
+##############################################################################
+
+# Attempt to set APP_HOME
+
+# Resolve links: $0 may be a link
+app_path=$0
+
+# Need this for daisy-chained symlinks.
+while
+APP_HOME=${app_path%"${app_path##*/}"}  # leaves a trailing /; empty if no leading path
+[ -h "$app_path" ]
+do
+ls=$( ls -ld "$app_path" )
+link=${ls#*' -> '}
+case $link in             #(
+/*)   app_path=$link ;; #(
+*)    app_path=$APP_HOME$link ;;
+esac
+done
+
+# This is normally unused
+# shellcheck disable=SC2034
+APP_BASE_NAME=${0##*/}
+# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036)
+APP_HOME=$( cd "${APP_HOME:-./}" > /dev/null && pwd -P ) || exit
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD=maximum
+
+warn () {
+echo "$*"
+} >&2
+
+die () {
+echo
+echo "$*"
+echo
+exit 1
+} >&2
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "$( uname )" in                #(
+CYGWIN* )         cygwin=true  ;; #(
+Darwin* )         darwin=true  ;; #(
+MSYS* | MINGW* )  msys=true    ;; #(
+NONSTOP* )        nonstop=true ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+# IBM's JDK on AIX uses strange locations for the executables
+JAVACMD=$JAVA_HOME/jre/sh/java
+else
+JAVACMD=$JAVA_HOME/bin/java
+fi
+if [ ! -x "$JAVACMD" ] ; then
+die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+else
+JAVACMD=java
+if ! command -v java >/dev/null 2>&1
+then
+die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+fi
+
+# Increase the maximum file descriptors if we can.
+if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then
+case $MAX_FD in #(
+max*)
+# In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked.
+# shellcheck disable=SC2039,SC3045
+MAX_FD=$( ulimit -H -n ) ||
+warn "Could not query maximum file descriptor limit"
+esac
+case $MAX_FD in  #(
+'' | soft) :;; #(
+*)
+# In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked.
+# shellcheck disable=SC2039,SC3045
+ulimit -n "$MAX_FD" ||
+warn "Could not set maximum file descriptor limit to $MAX_FD"
+esac
+fi
+
+# Collect all arguments for the java command, stacking in reverse order:
+#   * args from the command line
+#   * the main class name
+#   * -classpath
+#   * -D...appname settings
+#   * --module-path (only if needed)
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables.
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if "$cygwin" || "$msys" ; then
+APP_HOME=$( cygpath --path --mixed "$APP_HOME" )
+CLASSPATH=$( cygpath --path --mixed "$CLASSPATH" )
+
+JAVACMD=$( cygpath --unix "$JAVACMD" )
+
+# Now convert the arguments - kludge to limit ourselves to /bin/sh
+for arg do
+if
+case $arg in                                #(
+-*)   false ;;                            # don't mess with options #(
+/?*)  t=${arg#/} t=/${t%%/*}              # looks like a POSIX filepath
+[ -e "$t" ] ;;                      #(
+*)    false ;;
+esac
+then
+arg=$( cygpath --path --ignore --mixed "$arg" )
+fi
+# Roll the args list around exactly as many times as the number of
+# args, so each arg winds up back in the position where it started, but
+# possibly modified.
+#
+# NB: a `for` loop captures its iteration list before it begins, so
+# changing the positional parameters here affects neither the number of
+# iterations, nor the values presented in `arg`.
+shift                   # remove old arg
+set -- "$@" "$arg"      # push replacement arg
+done
+fi
+
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Collect all arguments for the java command:
+#   * DEFAULT_JVM_OPTS, JAVA_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments,
+#     and any embedded shellness will be escaped.
+#   * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be
+#     treated as '${Hostname}' itself on the command line.
+
+set -- \
+"-Dorg.gradle.appname=$APP_BASE_NAME" \
+-classpath "$CLASSPATH" \
+org.gradle.wrapper.GradleWrapperMain \
+"$@"
+
+# Stop when "xargs" is not available.
+if ! command -v xargs >/dev/null 2>&1
+then
+die "xargs is not available"
+fi
+
+# Use "xargs" to parse quoted args.
+#
+# With -n1 it outputs one arg per line, with the quotes and backslashes removed.
+#
+# In Bash we could simply go:
+#
+#   readarray ARGS < <( xargs -n1 <<<"$var" ) &&
+#   set -- "${ARGS[@]}" "$@"
+#
+# but POSIX shell has neither arrays nor command substitution, so instead we
+# post-process each arg (as a line of input to sed) to backslash-escape any
+# character that might be a shell metacharacter, then use eval to reverse
+# that process (while maintaining the separation between arguments), and wrap
+# the whole thing up as a single "set" statement.
+#
+# This will of course break if any of these variables contains a newline or
+# an unmatched quote.
+#
+
+eval "set -- $(
+printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" |
+xargs -n1 |
+sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' |
+tr '\n' ' '
+)" '"$@"'
+
+exec "$JAVACMD" "$@"

samples/client/others/java/restclient-enum-in-multipart/gradlew.bat

@@ -0,0 +1,92 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%"=="" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%"=="" set DIRNAME=.
+@rem This is normally unused
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if %ERRORLEVEL% equ 0 goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo. 1>&2
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2
+echo. 1>&2
+echo Please set the JAVA_HOME variable in your environment to match the 1>&2
+echo location of your Java installation. 1>&2
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if %ERRORLEVEL% equ 0 goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+set EXIT_CODE=%ERRORLEVEL%
+if %EXIT_CODE% equ 0 set EXIT_CODE=1
+if not ""=="%GRADLE_EXIT_CONSOLE%" exit %EXIT_CODE%
+exit /b %EXIT_CODE%
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

samples/client/others/java/restclient-enum-in-multipart/pom.xml

@@ -0,0 +1,285 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>org.openapitools</groupId>
+    <artifactId>openapi-java-client</artifactId>
+    <packaging>jar</packaging>
+    <name>openapi-java-client</name>
+    <version>1.0.0</version>
+    <url>https://github.com/openapitools/openapi-generator</url>
+    <description>OpenAPI Java</description>
+    <scm>
+        <connection>scm:git:git@github.com:openapitools/openapi-generator.git</connection>
+        <developerConnection>scm:git:git@github.com:openapitools/openapi-generator.git</developerConnection>
+        <url>https://github.com/openapitools/openapi-generator</url>
+    </scm>
+
+    <licenses>
+        <license>
+            <name>Unlicense</name>
+            <url>http://unlicense.org</url>
+            <distribution>repo</distribution>
+        </license>
+    </licenses>
+
+    <developers>
+        <developer>
+            <name>OpenAPI-Generator Contributors</name>
+            <email>team@openapitools.org</email>
+            <organization>OpenAPITools.org</organization>
+            <organizationUrl>http://openapitools.org</organizationUrl>
+        </developer>
+    </developers>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-enforcer-plugin</artifactId>
+                <version>3.4.0</version>
+                <executions>
+                    <execution>
+                        <id>enforce-maven</id>
+                        <goals>
+                            <goal>enforce</goal>
+                        </goals>
+                        <configuration>
+                            <rules>
+                                <requireMavenVersion>
+                                    <version>2.2.0</version>
+                                </requireMavenVersion>
+                            </rules>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>3.1.2</version>
+                <configuration>
+                    <systemPropertyVariables>
+                        <property>
+                            <name>loggerPath</name>
+                            <value>conf/log4j.properties</value>
+                        </property>
+                    </systemPropertyVariables>
+                    <argLine>-Xms512m -Xmx1500m</argLine>
+                    <parallel>methods</parallel>
+                    <reuseForks>false</reuseForks>
+                    <useUnlimitedThreads>true</useUnlimitedThreads>
+                </configuration>
+                <dependencies>
+                    <!--Custom provider and engine for Junit 5 to surefire-->
+                    <dependency>
+                        <groupId>org.junit.jupiter</groupId>
+                        <artifactId>junit-jupiter-engine</artifactId>
+                        <version>${junit-version}</version>
+                    </dependency>
+                </dependencies>
+            </plugin>
+            <plugin>
+                <artifactId>maven-dependency-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>copy-dependencies</goal>
+                        </goals>
+                        <configuration>
+                            <outputDirectory>${project.build.directory}/lib</outputDirectory>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+
+            <!-- attach test jar -->
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-jar-plugin</artifactId>
+                <version>3.3.0</version>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>test-jar</goal>
+                        </goals>
+                    </execution>
+                </executions>
+                <configuration>
+                </configuration>
+            </plugin>
+
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>build-helper-maven-plugin</artifactId>
+                <version>3.4.0</version>
+                <executions>
+                    <execution>
+                        <id>add_sources</id>
+                        <phase>generate-sources</phase>
+                        <goals>
+                            <goal>add-source</goal>
+                        </goals>
+                        <configuration>
+                            <sources>
+                                <source>src/main/java</source>
+                            </sources>
+                        </configuration>
+                    </execution>
+                    <execution>
+                        <id>add_test_sources</id>
+                        <phase>generate-test-sources</phase>
+                        <goals>
+                            <goal>add-test-source</goal>
+                        </goals>
+                        <configuration>
+                            <sources>
+                                <source>src/test/java</source>
+                            </sources>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.11.0</version>
+                <configuration>
+                    <source>17</source>
+                    <target>17</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-javadoc-plugin</artifactId>
+                <version>3.5.0</version>
+                <configuration>
+                    <doclint>none</doclint>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>attach-javadocs</id>
+                        <goals>
+                            <goal>jar</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-source-plugin</artifactId>
+                <version>3.3.0</version>
+                <executions>
+                    <execution>
+                        <id>attach-sources</id>
+                        <goals>
+                            <goal>jar-no-fork</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <profiles>
+        <profile>
+            <id>sign-artifacts</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-gpg-plugin</artifactId>
+                        <version>1.5</version>
+                        <executions>
+                            <execution>
+                                <id>sign-artifacts</id>
+                                <phase>verify</phase>
+                                <goals>
+                                    <goal>sign</goal>
+                                </goals>
+                            </execution>
+                        </executions>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
+    <dependencies>
+
+        <!-- @Nullable annotation -->
+        <dependency>
+            <groupId>com.google.code.findbugs</groupId>
+            <artifactId>jsr305</artifactId>
+            <version>3.0.2</version>
+        </dependency>
+
+        <!-- HTTP client: Spring RestClient -->
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-web</artifactId>
+            <version>${spring-web-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-context</artifactId>
+            <version>${spring-web-version}</version>
+        </dependency>
+
+        <!-- JSON processing: jackson -->
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-core</artifactId>
+            <version>${jackson-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-annotations</artifactId>
+            <version>${jackson-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson-databind-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.jakarta.rs</groupId>
+            <artifactId>jackson-jakarta-rs-json-provider</artifactId>
+            <version>${jackson-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openapitools</groupId>
+            <artifactId>jackson-databind-nullable</artifactId>
+            <version>${jackson-databind-nullable-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.datatype</groupId>
+            <artifactId>jackson-datatype-jsr310</artifactId>
+            <version>${jackson-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>jakarta.annotation</groupId>
+            <artifactId>jakarta.annotation-api</artifactId>
+            <version>${jakarta-annotation-version}</version>
+            <scope>provided</scope>
+        </dependency>
+
+        <!-- test dependencies -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>${junit-version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <spring-web-version>6.1.6</spring-web-version>
+        <jackson-version>2.17.1</jackson-version>
+        <jackson-databind-version>2.17.1</jackson-databind-version>
+        <jackson-databind-nullable-version>0.2.6</jackson-databind-nullable-version>
+        <jakarta-annotation-version>2.1.1</jakarta-annotation-version>
+        <beanvalidation-version>3.0.2</beanvalidation-version>
+        <junit-version>5.10.2</junit-version>
+    </properties>
+</project>

samples/client/others/java/restclient-enum-in-multipart/settings.gradle

@@ -0,0 +1 @@
+rootProject.name = "openapi-java-client"

samples/client/others/java/restclient-enum-in-multipart/src/main/AndroidManifest.xml

@@ -0,0 +1,3 @@
+<manifest package="org.openapitools.client" xmlns:android="http://schemas.android.com/apk/res/android">
+    <application />
+</manifest>

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ApiClient.java

@@ -0,0 +1,746 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import java.util.function.Consumer;
+import org.openapitools.jackson.nullable.JsonNullableModule;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.InvalidMediaTypeException;
+import org.springframework.http.MediaType;
+import org.springframework.http.converter.HttpMessageConverter;
+import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
+import org.springframework.util.CollectionUtils;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+import org.springframework.util.StringUtils;
+import org.springframework.web.client.RestClientException;
+import org.springframework.web.util.UriComponentsBuilder;
+import org.springframework.web.client.RestClient;
+import org.springframework.web.client.RestClient.ResponseSpec;
+import java.util.Optional;
+
+import java.text.DateFormat;
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.TimeZone;
+import java.util.function.Supplier;
+
+import jakarta.annotation.Nullable;
+
+import java.time.OffsetDateTime;
+
+import org.openapitools.client.auth.Authentication;
+import org.openapitools.client.auth.HttpBasicAuth;
+import org.openapitools.client.auth.HttpBearerAuth;
+import org.openapitools.client.auth.ApiKeyAuth;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class ApiClient extends JavaTimeFormatter {
+    public enum CollectionFormat {
+        CSV(","), TSV("\t"), SSV(" "), PIPES("|"), MULTI(null);
+
+        protected final String separator;
+        CollectionFormat(String separator) {
+            this.separator = separator;
+        }
+
+        protected String collectionToString(Collection<?> collection) {
+            return StringUtils.collectionToDelimitedString(collection, separator);
+        }
+    }
+
+    protected final HttpHeaders defaultHeaders = new HttpHeaders();
+    protected final MultiValueMap<String, String> defaultCookies = new LinkedMultiValueMap<>();
+
+    protected String basePath = "http://localhost:8080";
+
+    protected final RestClient restClient;
+    protected final DateFormat dateFormat;
+    protected final ObjectMapper objectMapper;
+
+    protected Map<String, Authentication> authentications;
+
+
+    public ApiClient() {
+        this(null);
+    }
+
+    public ApiClient(RestClient restClient) {
+        this(restClient, createDefaultDateFormat());
+    }
+
+    public ApiClient(ObjectMapper mapper, DateFormat format) {
+        this(null, mapper, format);
+    }
+
+    public ApiClient(RestClient restClient, ObjectMapper mapper, DateFormat format) {
+        this.objectMapper = mapper.copy();
+        this.restClient = Optional.ofNullable(restClient).orElseGet(() -> buildRestClient(this.objectMapper));
+        this.dateFormat = format;
+        this.init();
+    }
+
+    protected ApiClient(RestClient restClient, DateFormat format) {
+        this(restClient, createDefaultObjectMapper(format), format);
+    }
+
+    public static DateFormat createDefaultDateFormat() {
+        DateFormat dateFormat = new RFC3339DateFormat();
+        dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
+        return dateFormat;
+    }
+
+    public static ObjectMapper createDefaultObjectMapper(@Nullable DateFormat dateFormat) {
+        if (null == dateFormat) {
+            dateFormat = createDefaultDateFormat();
+        }
+        ObjectMapper mapper = new ObjectMapper();
+        mapper.setDateFormat(dateFormat);
+        mapper.registerModule(new JavaTimeModule());
+        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+        JsonNullableModule jnm = new JsonNullableModule();
+        mapper.registerModule(jnm);
+        return mapper;
+    }
+
+    protected void init() {
+        // Setup authentications (key: authentication name, value: authentication).
+        authentications = new HashMap<>();
+        authentications.put("basicAuth", new HttpBasicAuth());
+        // Prevent the authentications from being modified.
+        authentications = Collections.unmodifiableMap(authentications);
+    }
+
+    /**
+    * Build the RestClientBuilder used to make RestClient.
+    * @param mapper ObjectMapper used for serialize/deserialize
+    * @return RestClient
+    */
+    public static RestClient.Builder buildRestClientBuilder(ObjectMapper mapper) {
+        Consumer<List<HttpMessageConverter<?>>> messageConverters = converters -> {
+            converters.add(0, new MappingJackson2HttpMessageConverter(mapper));
+        };
+
+        return RestClient.builder().messageConverters(messageConverters);
+    }
+
+    /**
+     * Build the RestClientBuilder used to make RestClient.
+     * @return RestClient
+     */
+    public static RestClient.Builder buildRestClientBuilder() {
+        return buildRestClientBuilder(createDefaultObjectMapper(null));
+    }
+
+    /**
+     * Build the RestClient used to make HTTP requests.
+     * @param mapper ObjectMapper used for serialize/deserialize
+     * @return RestClient
+     */
+    public static RestClient buildRestClient(ObjectMapper mapper) {
+        return buildRestClientBuilder(mapper).build();
+    }
+
+    /**
+     * Build the RestClient used to make HTTP requests.
+     * @return RestClient
+     */
+    public static RestClient buildRestClient() {
+        return buildRestClientBuilder(createDefaultObjectMapper(null)).build();
+    }
+
+    /**
+     * Get the current base path
+     * @return String the base path
+     */
+    public String getBasePath() {
+        return basePath;
+    }
+
+    /**
+     * Set the base path, which should include the host
+     * @param basePath the base path
+     * @return ApiClient this client
+     */
+    public ApiClient setBasePath(String basePath) {
+        this.basePath = basePath;
+        return this;
+    }
+
+    /**
+     * Get authentications (key: authentication name, value: authentication).
+     * @return Map the currently configured authentication types
+     */
+    public Map<String, Authentication> getAuthentications() {
+        return authentications;
+    }
+
+    /**
+     * Get authentication for the given name.
+     *
+     * @param authName The authentication name
+     * @return The authentication, null if not found
+     */
+    public Authentication getAuthentication(String authName) {
+        return authentications.get(authName);
+    }
+
+    /**
+     * Helper method to set access token for the first Bearer authentication.
+     * @param bearerToken Bearer token
+     */
+    public void setBearerToken(String bearerToken) {
+        for (Authentication auth : authentications.values()) {
+            if (auth instanceof HttpBearerAuth) {
+                ((HttpBearerAuth) auth).setBearerToken(bearerToken);
+                return;
+            }
+        }
+        throw new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /**
+    * Helper method to set the supplier of access tokens for Bearer authentication.
+    *
+    * @param tokenSupplier the token supplier function
+    */
+    public void setBearerToken(Supplier<String> tokenSupplier) {
+        for (Authentication auth : authentications.values()) {
+            if (auth instanceof HttpBearerAuth) {
+                ((HttpBearerAuth) auth).setBearerToken(tokenSupplier);
+            return;
+            }
+        }
+        throw new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /**
+     * Helper method to set username for the first HTTP basic authentication.
+     * @param username the username
+     */
+    public void setUsername(String username) {
+        for (Authentication auth : authentications.values()) {
+            if (auth instanceof HttpBasicAuth) {
+                ((HttpBasicAuth) auth).setUsername(username);
+                return;
+            }
+        }
+        throw new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /**
+     * Helper method to set password for the first HTTP basic authentication.
+     * @param password the password
+     */
+    public void setPassword(String password) {
+        for (Authentication auth : authentications.values()) {
+            if (auth instanceof HttpBasicAuth) {
+                ((HttpBasicAuth) auth).setPassword(password);
+                return;
+            }
+        }
+        throw new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /**
+     * Helper method to set API key value for the first API key authentication.
+     * @param apiKey the API key
+     */
+    public void setApiKey(String apiKey) {
+        for (Authentication auth : authentications.values()) {
+            if (auth instanceof ApiKeyAuth) {
+                ((ApiKeyAuth) auth).setApiKey(apiKey);
+                return;
+            }
+        }
+        throw new RuntimeException("No API key authentication configured!");
+    }
+
+    /**
+     * Helper method to set API key prefix for the first API key authentication.
+     * @param apiKeyPrefix the API key prefix
+     */
+    public void setApiKeyPrefix(String apiKeyPrefix) {
+        for (Authentication auth : authentications.values()) {
+            if (auth instanceof ApiKeyAuth) {
+                ((ApiKeyAuth) auth).setApiKeyPrefix(apiKeyPrefix);
+                return;
+            }
+        }
+        throw new RuntimeException("No API key authentication configured!");
+    }
+
+    /**
+     * Set the User-Agent header's value (by adding to the default header map).
+     * @param userAgent the user agent string
+     * @return ApiClient this client
+     */
+    public ApiClient setUserAgent(String userAgent) {
+        addDefaultHeader("User-Agent", userAgent);
+        return this;
+    }
+
+    /**
+     * Add a default header.
+     *
+     * @param name The header's name
+     * @param value The header's value
+     * @return ApiClient this client
+     */
+    public ApiClient addDefaultHeader(String name, String value) {
+        if (defaultHeaders.containsKey(name)) {
+            defaultHeaders.remove(name);
+        }
+        defaultHeaders.add(name, value);
+        return this;
+    }
+
+    /**
+     * Add a default cookie.
+     *
+     * @param name The cookie's name
+     * @param value The cookie's value
+     * @return ApiClient this client
+     */
+    public ApiClient addDefaultCookie(String name, String value) {
+        if (defaultCookies.containsKey(name)) {
+            defaultCookies.remove(name);
+        }
+        defaultCookies.add(name, value);
+        return this;
+    }
+
+    /**
+     * Get the date format used to parse/format date parameters.
+     * @return DateFormat format
+     */
+    public DateFormat getDateFormat() {
+        return dateFormat;
+    }
+
+    /**
+     * Parse the given string into Date object.
+     */
+    public Date parseDate(String str) {
+        try {
+            return dateFormat.parse(str);
+        } catch (ParseException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Format the given Date object into string.
+     */
+    public String formatDate(Date date) {
+        return dateFormat.format(date);
+    }
+
+    /**
+     * Get the ObjectMapper used to make HTTP requests.
+     * @return ObjectMapper objectMapper
+     */
+    public ObjectMapper getObjectMapper() {
+        return objectMapper;
+    }
+
+    /**
+     * Get the RestClient used to make HTTP requests.
+     * @return RestClient restClient
+     */
+    public RestClient getRestClient() {
+        return restClient;
+    }
+
+    /**
+     * Format the given parameter object into string.
+     * @param param the object to convert
+     * @return String the parameter represented as a String
+     */
+    public String parameterToString(Object param) {
+        if (param == null) {
+            return "";
+        } else if (param instanceof Date) {
+            return formatDate( (Date) param);
+        } else if (param instanceof OffsetDateTime) {
+            return formatOffsetDateTime((OffsetDateTime) param);
+        } else if (param instanceof Collection) {
+            StringBuilder b = new StringBuilder();
+            for(Object o : (Collection<?>) param) {
+                if(b.length() > 0) {
+                    b.append(",");
+                }
+                b.append(String.valueOf(o));
+            }
+            return b.toString();
+        } else {
+            return String.valueOf(param);
+        }
+    }
+
+    /**
+     * Converts a parameter to a {@link MultiValueMap} for use in REST requests
+     * @param collectionFormat The format to convert to
+     * @param name The name of the parameter
+     * @param value The parameter's value
+     * @return a Map containing the String value(s) of the input parameter
+     */
+    public MultiValueMap<String, String> parameterToMultiValueMap(CollectionFormat collectionFormat, String name, Object value) {
+        final MultiValueMap<String, String> params = new LinkedMultiValueMap<>();
+
+        if (name == null || name.isEmpty() || value == null) {
+            return params;
+        }
+
+        if(collectionFormat == null) {
+            collectionFormat = CollectionFormat.CSV;
+        }
+
+        if (value instanceof Map) {
+            @SuppressWarnings("unchecked")
+            final Map<String, Object> valuesMap = (Map<String, Object>) value;
+            for (final Entry<String, Object> entry : valuesMap.entrySet()) {
+                params.add(entry.getKey(), parameterToString(entry.getValue()));
+            }
+            return params;
+        }
+
+        Collection<?> valueCollection = null;
+        if (value instanceof Collection) {
+            valueCollection = (Collection<?>) value;
+        } else {
+            params.add(name, parameterToString(value));
+            return params;
+        }
+
+        if (valueCollection.isEmpty()){
+            return params;
+        }
+
+        if (collectionFormat.equals(CollectionFormat.MULTI)) {
+            for (Object item : valueCollection) {
+                params.add(name, parameterToString(item));
+            }
+            return params;
+        }
+
+        List<String> values = new ArrayList<>();
+        for(Object o : valueCollection) {
+            values.add(parameterToString(o));
+        }
+        params.add(name, collectionFormat.collectionToString(values));
+
+        return params;
+    }
+
+    /**
+    * Check if the given {@code String} is a JSON MIME.
+    * @param mediaType the input MediaType
+    * @return boolean true if the MediaType represents JSON, false otherwise
+    */
+    public boolean isJsonMime(String mediaType) {
+        // "* / *" is default to JSON
+        if ("*/*".equals(mediaType)) {
+            return true;
+        }
+
+        try {
+            return isJsonMime(MediaType.parseMediaType(mediaType));
+        } catch (InvalidMediaTypeException e) {
+        }
+        return false;
+    }
+
+    /**
+     * Check if the given MIME is a JSON MIME.
+     * JSON MIME examples:
+     *     application/json
+     *     application/json; charset=UTF8
+     *     APPLICATION/JSON
+     * @param mediaType the input MediaType
+     * @return boolean true if the MediaType represents JSON, false otherwise
+     */
+    public boolean isJsonMime(MediaType mediaType) {
+        return mediaType != null && (MediaType.APPLICATION_JSON.isCompatibleWith(mediaType) || mediaType.getSubtype().matches("^.*(\\+json|ndjson)[;]?\\s*$"));
+    }
+
+    /**
+    * Check if the given {@code String} is a Problem JSON MIME (RFC-7807).
+    * @param mediaType the input MediaType
+    * @return boolean true if the MediaType represents Problem JSON, false otherwise
+    */
+    public boolean isProblemJsonMime(String mediaType) {
+        return "application/problem+json".equalsIgnoreCase(mediaType);
+    }
+
+    /**
+     * Select the Accept header's value from the given accepts array:
+     *     if JSON exists in the given array, use it;
+     *     otherwise use all of them (joining into a string)
+     *
+     * @param accepts The accepts array to select from
+     * @return List The list of MediaTypes to use for the Accept header
+     */
+    public List<MediaType> selectHeaderAccept(String[] accepts) {
+        if (accepts.length == 0) {
+            return null;
+        }
+        for (String accept : accepts) {
+            MediaType mediaType = MediaType.parseMediaType(accept);
+            if (isJsonMime(mediaType) && !isProblemJsonMime(accept)) {
+                return Collections.singletonList(mediaType);
+            }
+        }
+        return MediaType.parseMediaTypes(StringUtils.arrayToCommaDelimitedString(accepts));
+    }
+
+    /**
+     * Select the Content-Type header's value from the given array:
+     *     if JSON exists in the given array, use it;
+     *     otherwise use the first one of the array.
+     *
+     * @param contentTypes The Content-Type array to select from
+     * @return MediaType The Content-Type header to use. If the given array is empty, null will be returned.
+     */
+    public MediaType selectHeaderContentType(String[] contentTypes) {
+        if (contentTypes.length == 0) {
+            return null;
+        }
+        for (String contentType : contentTypes) {
+            MediaType mediaType = MediaType.parseMediaType(contentType);
+            if (isJsonMime(mediaType)) {
+                return mediaType;
+            }
+        }
+        return MediaType.parseMediaType(contentTypes[0]);
+    }
+
+    /**
+    * Select the body to use for the request
+    *
+    * @param obj the body object
+    * @param formParams the form parameters
+    * @param contentType the content type of the request
+    * @return Object the selected body
+    */
+    protected Object selectBody(Object obj, MultiValueMap<String, Object> formParams, MediaType contentType) {
+        boolean isForm = MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType) || MediaType.APPLICATION_FORM_URLENCODED.isCompatibleWith(contentType);
+        return isForm ? formParams : obj;
+    }
+
+    /**
+     * Invoke API by sending HTTP request with the given options.
+     *
+     * @param <T> the return type to use
+     * @param path The sub-path of the HTTP URL
+     * @param method The request method
+     * @param pathParams The path parameters
+     * @param queryParams The query parameters
+     * @param body The request body object
+     * @param headerParams The header parameters
+     * @param formParams The form parameters
+     * @param accept The request's Accept header
+     * @param contentType The request's Content-Type header
+     * @param authNames The authentications to apply
+     * @param returnType The return type into which to deserialize the response
+     * @return The response body in chosen type
+     */
+    public <T> ResponseSpec invokeAPI(String path, HttpMethod method, Map<String, Object> pathParams, MultiValueMap<String, String> queryParams, Object body, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams, MultiValueMap<String, Object> formParams, List<MediaType> accept, MediaType contentType, String[] authNames, ParameterizedTypeReference<T> returnType) throws RestClientException {
+        final RestClient.RequestBodySpec requestBuilder = prepareRequest(path, method, pathParams, queryParams, body, headerParams, cookieParams, formParams, accept, contentType, authNames);
+        return requestBuilder.retrieve();
+    }
+
+    /**
+     * Include queryParams in uriParams taking into account the paramName
+     * @param queryParams The query parameters
+     * @param uriParams The path parameters
+     * return templatized query string
+     */
+    protected String generateQueryUri(MultiValueMap<String, String> queryParams, Map<String, Object> uriParams) {
+        StringBuilder queryBuilder = new StringBuilder();
+        queryParams.forEach((name, values) -> {
+            if (CollectionUtils.isEmpty(values)) {
+                if (queryBuilder.length() != 0) {
+                    queryBuilder.append('&');
+                }
+                queryBuilder.append(name);
+            } else {
+                int valueItemCounter = 0;
+                for (Object value : values) {
+                    if (queryBuilder.length() != 0) {
+                        queryBuilder.append('&');
+                    }
+                    queryBuilder.append(name);
+                    if (value != null) {
+                        String templatizedKey = name + valueItemCounter++;
+                        uriParams.put(templatizedKey, value.toString());
+                        queryBuilder.append('=').append("{").append(templatizedKey).append("}");
+                    }
+                }
+            }
+        });
+        return queryBuilder.toString();
+    }
+
+    protected RestClient.RequestBodySpec prepareRequest(String path, HttpMethod method, Map<String, Object> pathParams,
+        MultiValueMap<String, String> queryParams, Object body, HttpHeaders headerParams,
+        MultiValueMap<String, String> cookieParams, MultiValueMap<String, Object> formParams, List<MediaType> accept,
+        MediaType contentType, String[] authNames) {
+        updateParamsForAuth(authNames, queryParams, headerParams, cookieParams);
+
+        final UriComponentsBuilder builder = UriComponentsBuilder.fromUriString(basePath).path(path);
+
+        String finalUri = builder.build(false).toUriString();
+        Map<String, Object> uriParams = new HashMap<>();
+        uriParams.putAll(pathParams);
+
+        if (queryParams != null && !queryParams.isEmpty()) {
+            //Include queryParams in uriParams taking into account the paramName
+            String queryUri = generateQueryUri(queryParams, uriParams);
+            //Append to finalUri the templatized query string like "?param1={param1Value}&.......
+            finalUri += "?" + queryUri;
+        }
+
+        final RestClient.RequestBodySpec requestBuilder = restClient.method(method).uri(finalUri, uriParams);
+
+        if (accept != null) {
+            requestBuilder.accept(accept.toArray(new MediaType[accept.size()]));
+        }
+        if(contentType != null) {
+            requestBuilder.contentType(contentType);
+        }
+
+        addHeadersToRequest(headerParams, requestBuilder);
+        addHeadersToRequest(defaultHeaders, requestBuilder);
+        addCookiesToRequest(cookieParams, requestBuilder);
+        addCookiesToRequest(defaultCookies, requestBuilder);
+
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
+        var selectedBody = selectBody(body, formParams, contentType);
+        if (selectedBody != null) {
+          requestBuilder.body(selectedBody);
+        }
+
+        return requestBuilder;
+    }
+
+    /**
+     * Add headers to the request that is being built
+     * @param headers The headers to add
+     * @param requestBuilder The current request
+     */
+    protected void addHeadersToRequest(HttpHeaders headers, RestClient.RequestBodySpec requestBuilder) {
+        for (Entry<String, List<String>> entry : headers.entrySet()) {
+            List<String> values = entry.getValue();
+            for(String value : values) {
+                if (value != null) {
+                    requestBuilder.header(entry.getKey(), value);
+                }
+            }
+        }
+    }
+
+     /**
+     * Add cookies to the request that is being built
+     *
+     * @param cookies        The cookies to add
+     * @param requestBuilder The current request
+     */
+    protected void addCookiesToRequest(MultiValueMap<String, String> cookies, RestClient.RequestBodySpec requestBuilder) {
+        if (!cookies.isEmpty()) {
+            requestBuilder.header("Cookie", buildCookieHeader(cookies));
+        }
+    }
+
+    /**
+     * Build cookie header. Keeps a single value per cookie (as per <a href="https://tools.ietf.org/html/rfc6265#section-5.3">
+     * RFC6265 section 5.3</a>).
+     *
+     * @param cookies map all cookies
+     * @return header string for cookies.
+     */
+    protected String buildCookieHeader(MultiValueMap<String, String> cookies) {
+        final StringBuilder cookieValue = new StringBuilder();
+        String delimiter = "";
+        for (final Map.Entry<String, List<String>> entry : cookies.entrySet()) {
+            final String value = entry.getValue().get(entry.getValue().size() - 1);
+            cookieValue.append(String.format("%s%s=%s", delimiter, entry.getKey(), value));
+            delimiter = "; ";
+        }
+        return cookieValue.toString();
+    }
+
+    /**
+     * Update query and header parameters based on authentication settings.
+     *
+     * @param authNames The authentications to apply
+     * @param queryParams The query parameters
+     * @param headerParams The header parameters
+     * @param cookieParams the cookie parameters
+     */
+    protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams) {
+        for (String authName : authNames) {
+            Authentication auth = authentications.get(authName);
+            if (auth == null) {
+                throw new RestClientException("Authentication undefined: " + authName);
+            }
+            auth.applyToParams(queryParams, headerParams, cookieParams);
+        }
+    }
+
+    /**
+    * Formats the specified collection path parameter to a string value.
+    *
+    * @param collectionFormat The collection format of the parameter.
+    * @param values The values of the parameter.
+    * @return String representation of the parameter
+    */
+    public String collectionPathParameterToString(CollectionFormat collectionFormat, Collection<?> values) {
+        // create the value based on the collection format
+        if (CollectionFormat.MULTI.equals(collectionFormat)) {
+            // not valid for path params
+            return parameterToString(values);
+        }
+
+         // collectionFormat is assumed to be "csv" by default
+        if(collectionFormat == null) {
+            collectionFormat = CollectionFormat.CSV;
+        }
+
+        return collectionFormat.collectionToString(values);
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/JavaTimeFormatter.java

@@ -0,0 +1,64 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+package org.openapitools.client;
+
+import java.time.OffsetDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+
+/**
+ * Class that add parsing/formatting support for Java 8+ {@code OffsetDateTime} class.
+ * It's generated for java clients when {@code AbstractJavaCodegen#dateLibrary} specified as {@code java8}.
+ */
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class JavaTimeFormatter {
+
+    private DateTimeFormatter offsetDateTimeFormatter = DateTimeFormatter.ISO_OFFSET_DATE_TIME;
+
+    /**
+     * Get the date format used to parse/format {@code OffsetDateTime} parameters.
+     * @return DateTimeFormatter
+     */
+    public DateTimeFormatter getOffsetDateTimeFormatter() {
+        return offsetDateTimeFormatter;
+    }
+
+    /**
+     * Set the date format used to parse/format {@code OffsetDateTime} parameters.
+     * @param offsetDateTimeFormatter {@code DateTimeFormatter}
+     */
+    public void setOffsetDateTimeFormatter(DateTimeFormatter offsetDateTimeFormatter) {
+        this.offsetDateTimeFormatter = offsetDateTimeFormatter;
+    }
+
+    /**
+     * Parse the given string into {@code OffsetDateTime} object.
+     * @param str String
+     * @return {@code OffsetDateTime}
+     */
+    public OffsetDateTime parseOffsetDateTime(String str) {
+        try {
+            return OffsetDateTime.parse(str, offsetDateTimeFormatter);
+        } catch (DateTimeParseException e) {
+            throw new RuntimeException(e);
+        }
+    }
+    /**
+     * Format the given {@code OffsetDateTime} object into string.
+     * @param offsetDateTime {@code OffsetDateTime}
+     * @return {@code OffsetDateTime} in string format
+     */
+    public String formatOffsetDateTime(OffsetDateTime offsetDateTime) {
+        return offsetDateTimeFormatter.format(offsetDateTime);
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/RFC3339DateFormat.java

@@ -0,0 +1,58 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+package org.openapitools.client;
+
+import com.fasterxml.jackson.databind.util.StdDateFormat;
+
+import java.text.DateFormat;
+import java.text.FieldPosition;
+import java.text.ParsePosition;
+import java.util.Date;
+import java.text.DecimalFormat;
+import java.util.GregorianCalendar;
+import java.util.TimeZone;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class RFC3339DateFormat extends DateFormat {
+  private static final long serialVersionUID = 1L;
+  private static final TimeZone TIMEZONE_Z = TimeZone.getTimeZone("UTC");
+
+  private final StdDateFormat fmt = new StdDateFormat()
+          .withTimeZone(TIMEZONE_Z)
+          .withColonInTimeZone(true);
+
+  public RFC3339DateFormat() {
+    this.calendar = new GregorianCalendar();
+    this.numberFormat = new DecimalFormat();
+  }
+
+  @Override
+  public Date parse(String source) {
+    return parse(source, new ParsePosition(0));
+  }
+
+  @Override
+  public Date parse(String source, ParsePosition pos) {
+    return fmt.parse(source, pos);
+  }
+
+  @Override
+  public StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition) {
+    return fmt.format(date, toAppendTo, fieldPosition);
+  }
+
+  @Override
+  public Object clone() {
+    return super.clone();
+  }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java

@@ -0,0 +1,100 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+package org.openapitools.client;
+
+import java.io.IOException;
+import java.time.Instant;
+import java.time.OffsetDateTime;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.Temporal;
+import java.time.temporal.TemporalAccessor;
+import java.util.function.BiFunction;
+import java.util.function.Function;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeFeature;
+import com.fasterxml.jackson.datatype.jsr310.deser.InstantDeserializer;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class RFC3339InstantDeserializer<T extends Temporal> extends InstantDeserializer<T> {
+    private static final long serialVersionUID = 1L;
+    private final static boolean DEFAULT_NORMALIZE_ZONE_ID = JavaTimeFeature.NORMALIZE_DESERIALIZED_ZONE_ID.enabledByDefault();
+    private final static boolean DEFAULT_ALWAYS_ALLOW_STRINGIFIED_DATE_TIMESTAMPS
+    = JavaTimeFeature.ALWAYS_ALLOW_STRINGIFIED_DATE_TIMESTAMPS.enabledByDefault();
+
+    public static final RFC3339InstantDeserializer<Instant> INSTANT = new RFC3339InstantDeserializer<>(
+        Instant.class, DateTimeFormatter.ISO_INSTANT,
+        Instant::from,
+        a -> Instant.ofEpochMilli( a.value ),
+        a -> Instant.ofEpochSecond( a.integer, a.fraction ),
+        null,
+        true, // yes, replace zero offset with Z
+        DEFAULT_NORMALIZE_ZONE_ID,
+        DEFAULT_ALWAYS_ALLOW_STRINGIFIED_DATE_TIMESTAMPS
+    );
+
+    public static final RFC3339InstantDeserializer<OffsetDateTime> OFFSET_DATE_TIME = new RFC3339InstantDeserializer<>(
+        OffsetDateTime.class, DateTimeFormatter.ISO_OFFSET_DATE_TIME,
+        OffsetDateTime::from,
+        a -> OffsetDateTime.ofInstant( Instant.ofEpochMilli( a.value ), a.zoneId ),
+        a -> OffsetDateTime.ofInstant( Instant.ofEpochSecond( a.integer, a.fraction ), a.zoneId ),
+        (d, z) -> ( d.isEqual( OffsetDateTime.MIN ) || d.isEqual( OffsetDateTime.MAX ) ?
+        d :
+        d.withOffsetSameInstant( z.getRules().getOffset( d.toLocalDateTime() ) ) ),
+        true, // yes, replace zero offset with Z
+        DEFAULT_NORMALIZE_ZONE_ID,
+        DEFAULT_ALWAYS_ALLOW_STRINGIFIED_DATE_TIMESTAMPS
+    );
+
+    public static final RFC3339InstantDeserializer<ZonedDateTime> ZONED_DATE_TIME = new RFC3339InstantDeserializer<>(
+        ZonedDateTime.class, DateTimeFormatter.ISO_ZONED_DATE_TIME,
+        ZonedDateTime::from,
+        a -> ZonedDateTime.ofInstant( Instant.ofEpochMilli( a.value ), a.zoneId ),
+        a -> ZonedDateTime.ofInstant( Instant.ofEpochSecond( a.integer, a.fraction ), a.zoneId ),
+        ZonedDateTime::withZoneSameInstant,
+        false, // keep zero offset and Z separate since zones explicitly supported
+        DEFAULT_NORMALIZE_ZONE_ID,
+        DEFAULT_ALWAYS_ALLOW_STRINGIFIED_DATE_TIMESTAMPS
+    );
+
+    protected RFC3339InstantDeserializer(
+            Class<T> supportedType,
+            DateTimeFormatter formatter,
+            Function<TemporalAccessor, T> parsedToValue,
+            Function<FromIntegerArguments, T> fromMilliseconds,
+            Function<FromDecimalArguments, T> fromNanoseconds,
+            BiFunction<T, ZoneId, T> adjust,
+            boolean replaceZeroOffsetAsZ,
+            boolean normalizeZoneId,
+            boolean readNumericStringsAsTimestamp) {
+        super(
+                supportedType,
+                formatter,
+                parsedToValue,
+                fromMilliseconds,
+                fromNanoseconds,
+                adjust,
+                replaceZeroOffsetAsZ,
+                normalizeZoneId,
+                readNumericStringsAsTimestamp
+        );
+    }
+
+    @Override
+    protected T _fromString(JsonParser p, DeserializationContext ctxt, String string0) throws IOException {
+        return super._fromString(p, ctxt, string0.replace( ' ', 'T' ));
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/RFC3339JavaTimeModule.java

@@ -0,0 +1,32 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+package org.openapitools.client;
+
+import java.time.Instant;
+import java.time.OffsetDateTime;
+import java.time.ZonedDateTime;
+
+import com.fasterxml.jackson.databind.module.SimpleModule;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class RFC3339JavaTimeModule extends SimpleModule {
+    private static final long serialVersionUID = 1L;
+
+    public RFC3339JavaTimeModule() {
+        super("RFC3339JavaTimeModule");
+
+        addDeserializer(Instant.class, RFC3339InstantDeserializer.INSTANT);
+        addDeserializer(OffsetDateTime.class, RFC3339InstantDeserializer.OFFSET_DATE_TIME);
+        addDeserializer(ZonedDateTime.class, RFC3339InstantDeserializer.ZONED_DATE_TIME);
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ServerConfiguration.java

@@ -0,0 +1,72 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import java.util.Map;
+
+/**
+ * Representing a Server configuration.
+ */
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class ServerConfiguration {
+    public String URL;
+    public String description;
+    public Map<String, ServerVariable> variables;
+
+    /**
+     * @param URL A URL to the target host.
+     * @param description A description of the host designated by the URL.
+     * @param variables A map between a variable name and its value. The value is used for substitution in the server's URL template.
+     */
+    public ServerConfiguration(String URL, String description, Map<String, ServerVariable> variables) {
+        this.URL = URL;
+        this.description = description;
+        this.variables = variables;
+    }
+
+    /**
+     * Format URL template using given variables.
+     *
+     * @param variables A map between a variable name and its value.
+     * @return Formatted URL.
+     */
+    public String URL(Map<String, String> variables) {
+        String url = this.URL;
+
+        // go through variables and replace placeholders
+        for (Map.Entry<String, ServerVariable> variable: this.variables.entrySet()) {
+            String name = variable.getKey();
+            ServerVariable serverVariable = variable.getValue();
+            String value = serverVariable.defaultValue;
+
+            if (variables != null && variables.containsKey(name)) {
+                value = variables.get(name);
+                if (serverVariable.enumValues.size() > 0 && !serverVariable.enumValues.contains(value)) {
+                    throw new IllegalArgumentException("The variable " + name + " in the server URL has invalid value " + value + ".");
+                }
+            }
+            url = url.replace("{" + name + "}", value);
+        }
+        return url;
+    }
+
+    /**
+     * Format URL template using default server variables.
+     *
+     * @return Formatted URL.
+     */
+    public String URL() {
+        return URL(null);
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ServerVariable.java

@@ -0,0 +1,37 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import java.util.HashSet;
+
+/**
+ * Representing a Server Variable for server URL template substitution.
+ */
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class ServerVariable {
+    public String description;
+    public String defaultValue;
+    public HashSet<String> enumValues = null;
+
+    /**
+     * @param description A description for the server variable.
+     * @param defaultValue The default value to use for substitution.
+     * @param enumValues An enumeration of string values to be used if the substitution options are from a limited set.
+     */
+    public ServerVariable(String description, String defaultValue, HashSet<String> enumValues) {
+        this.description = description;
+        this.defaultValue = defaultValue;
+        this.enumValues = enumValues;
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/StringUtil.java

@@ -0,0 +1,83 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import java.util.Collection;
+import java.util.Iterator;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class StringUtil {
+  /**
+   * Check if the given array contains the given value (with case-insensitive comparison).
+   *
+   * @param array The array
+   * @param value The value to search
+   * @return true if the array contains the value
+   */
+  public static boolean containsIgnoreCase(String[] array, String value) {
+    for (String str : array) {
+      if (value == null && str == null) {
+        return true;
+      }
+      if (value != null && value.equalsIgnoreCase(str)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Join an array of strings with the given separator.
+   * <p>
+   * Note: This might be replaced by utility method from commons-lang or guava someday
+   * if one of those libraries is added as dependency.
+   * </p>
+   *
+   * @param array     The array of strings
+   * @param separator The separator
+   * @return the resulting string
+   */
+  public static String join(String[] array, String separator) {
+    int len = array.length;
+    if (len == 0) {
+      return "";
+    }
+
+    StringBuilder out = new StringBuilder();
+    out.append(array[0]);
+    for (int i = 1; i < len; i++) {
+      out.append(separator).append(array[i]);
+    }
+    return out.toString();
+  }
+
+  /**
+   * Join a list of strings with the given separator.
+   *
+   * @param list      The list of strings
+   * @param separator The separator
+   * @return the resulting string
+   */
+  public static String join(Collection<String> list, String separator) {
+    Iterator<String> iterator = list.iterator();
+    StringBuilder out = new StringBuilder();
+    if (iterator.hasNext()) {
+      out.append(iterator.next());
+    }
+    while (iterator.hasNext()) {
+      out.append(separator).append(iterator.next());
+    }
+    return out.toString();
+  }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/api/BasApi.java

@@ -0,0 +1,157 @@
+package org.openapitools.client.api;
+
+import org.openapitools.client.ApiClient;
+
+import org.openapitools.client.model.DataChannel;
+import org.openapitools.client.model.DataDirection;
+import java.io.File;
+import org.openapitools.client.model.InlineObject;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Arrays;
+import java.util.stream.Collectors;
+
+import org.springframework.core.io.FileSystemResource;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.client.RestClient.ResponseSpec;
+import org.springframework.web.client.RestClientResponseException;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class BasApi {
+    private ApiClient apiClient;
+
+    public BasApi() {
+        this(new ApiClient());
+    }
+
+    public BasApi(ApiClient apiClient) {
+        this.apiClient = apiClient;
+    }
+
+    public ApiClient getApiClient() {
+        return apiClient;
+    }
+
+    public void setApiClient(ApiClient apiClient) {
+        this.apiClient = apiClient;
+    }
+
+    /**
+     * Creates a new message
+     * Creates a new message
+     * <p><b>201</b> - The message was created.
+     * @param fileContent The message payload
+     * @param idempotencyKey The idempotencyKey parameter
+     * @param dataDirection The dataDirection parameter
+     * @param dataChannel The dataChannel parameter
+     * @return InlineObject
+     * @throws RestClientResponseException if an error occurs while attempting to invoke the API
+     */
+    private ResponseSpec createMessageRequestCreation(@jakarta.annotation.Nonnull File fileContent, @jakarta.annotation.Nonnull String idempotencyKey, @jakarta.annotation.Nonnull DataDirection dataDirection, @jakarta.annotation.Nonnull DataChannel dataChannel) throws RestClientResponseException {
+        Object postBody = null;
+        // verify the required parameter 'fileContent' is set
+        if (fileContent == null) {
+            throw new RestClientResponseException("Missing the required parameter 'fileContent' when calling createMessage", HttpStatus.BAD_REQUEST.value(), HttpStatus.BAD_REQUEST.getReasonPhrase(), null, null, null);
+        }
+        // verify the required parameter 'idempotencyKey' is set
+        if (idempotencyKey == null) {
+            throw new RestClientResponseException("Missing the required parameter 'idempotencyKey' when calling createMessage", HttpStatus.BAD_REQUEST.value(), HttpStatus.BAD_REQUEST.getReasonPhrase(), null, null, null);
+        }
+        // verify the required parameter 'dataDirection' is set
+        if (dataDirection == null) {
+            throw new RestClientResponseException("Missing the required parameter 'dataDirection' when calling createMessage", HttpStatus.BAD_REQUEST.value(), HttpStatus.BAD_REQUEST.getReasonPhrase(), null, null, null);
+        }
+        // verify the required parameter 'dataChannel' is set
+        if (dataChannel == null) {
+            throw new RestClientResponseException("Missing the required parameter 'dataChannel' when calling createMessage", HttpStatus.BAD_REQUEST.value(), HttpStatus.BAD_REQUEST.getReasonPhrase(), null, null, null);
+        }
+        // create path and map variables
+        final Map<String, Object> pathParams = new HashMap<>();
+
+        final MultiValueMap<String, String> queryParams = new LinkedMultiValueMap<>();
+        final HttpHeaders headerParams = new HttpHeaders();
+        final MultiValueMap<String, String> cookieParams = new LinkedMultiValueMap<>();
+        final MultiValueMap<String, Object> formParams = new LinkedMultiValueMap<>();
+
+        if (fileContent != null)
+            formParams.add("fileContent", new FileSystemResource(fileContent));
+        if (idempotencyKey != null)
+            formParams.add("idempotencyKey", idempotencyKey);
+        if (dataDirection != null)
+            formParams.add("dataDirection", dataDirection);
+        if (dataChannel != null)
+            formParams.add("dataChannel", dataChannel);
+
+        final String[] localVarAccepts = { 
+            "application/json"
+        };
+        final List<MediaType> localVarAccept = apiClient.selectHeaderAccept(localVarAccepts);
+        final String[] localVarContentTypes = { 
+            "multipart/form-data"
+        };
+        final MediaType localVarContentType = apiClient.selectHeaderContentType(localVarContentTypes);
+
+        String[] localVarAuthNames = new String[] { "basicAuth" };
+
+        ParameterizedTypeReference<InlineObject> localVarReturnType = new ParameterizedTypeReference<>() {};
+        return apiClient.invokeAPI("/messages", HttpMethod.POST, pathParams, queryParams, postBody, headerParams, cookieParams, formParams, localVarAccept, localVarContentType, localVarAuthNames, localVarReturnType);
+    }
+
+    /**
+     * Creates a new message
+     * Creates a new message
+     * <p><b>201</b> - The message was created.
+     * @param fileContent The message payload
+     * @param idempotencyKey The idempotencyKey parameter
+     * @param dataDirection The dataDirection parameter
+     * @param dataChannel The dataChannel parameter
+     * @return InlineObject
+     * @throws RestClientResponseException if an error occurs while attempting to invoke the API
+     */
+    public InlineObject createMessage(@jakarta.annotation.Nonnull File fileContent, @jakarta.annotation.Nonnull String idempotencyKey, @jakarta.annotation.Nonnull DataDirection dataDirection, @jakarta.annotation.Nonnull DataChannel dataChannel) throws RestClientResponseException {
+        ParameterizedTypeReference<InlineObject> localVarReturnType = new ParameterizedTypeReference<>() {};
+        return createMessageRequestCreation(fileContent, idempotencyKey, dataDirection, dataChannel).body(localVarReturnType);
+    }
+
+    /**
+     * Creates a new message
+     * Creates a new message
+     * <p><b>201</b> - The message was created.
+     * @param fileContent The message payload
+     * @param idempotencyKey The idempotencyKey parameter
+     * @param dataDirection The dataDirection parameter
+     * @param dataChannel The dataChannel parameter
+     * @return ResponseEntity&lt;InlineObject&gt;
+     * @throws RestClientResponseException if an error occurs while attempting to invoke the API
+     */
+    public ResponseEntity<InlineObject> createMessageWithHttpInfo(@jakarta.annotation.Nonnull File fileContent, @jakarta.annotation.Nonnull String idempotencyKey, @jakarta.annotation.Nonnull DataDirection dataDirection, @jakarta.annotation.Nonnull DataChannel dataChannel) throws RestClientResponseException {
+        ParameterizedTypeReference<InlineObject> localVarReturnType = new ParameterizedTypeReference<>() {};
+        return createMessageRequestCreation(fileContent, idempotencyKey, dataDirection, dataChannel).toEntity(localVarReturnType);
+    }
+
+    /**
+     * Creates a new message
+     * Creates a new message
+     * <p><b>201</b> - The message was created.
+     * @param fileContent The message payload
+     * @param idempotencyKey The idempotencyKey parameter
+     * @param dataDirection The dataDirection parameter
+     * @param dataChannel The dataChannel parameter
+     * @return ResponseSpec
+     * @throws RestClientResponseException if an error occurs while attempting to invoke the API
+     */
+    public ResponseSpec createMessageWithResponseSpec(@jakarta.annotation.Nonnull File fileContent, @jakarta.annotation.Nonnull String idempotencyKey, @jakarta.annotation.Nonnull DataDirection dataDirection, @jakarta.annotation.Nonnull DataChannel dataChannel) throws RestClientResponseException {
+        return createMessageRequestCreation(fileContent, idempotencyKey, dataDirection, dataChannel);
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/auth/ApiKeyAuth.java

@@ -0,0 +1,75 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.auth;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.util.MultiValueMap;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class ApiKeyAuth implements Authentication {
+    private final String location;
+    private final String paramName;
+
+    private String apiKey;
+    private String apiKeyPrefix;
+
+    public ApiKeyAuth(String location, String paramName) {
+        this.location = location;
+        this.paramName = paramName;
+    }
+
+    public String getLocation() {
+        return location;
+    }
+
+    public String getParamName() {
+        return paramName;
+    }
+
+    public String getApiKey() {
+        return apiKey;
+    }
+
+    public void setApiKey(String apiKey) {
+        this.apiKey = apiKey;
+    }
+
+    public String getApiKeyPrefix() {
+        return apiKeyPrefix;
+    }
+
+    public void setApiKeyPrefix(String apiKeyPrefix) {
+        this.apiKeyPrefix = apiKeyPrefix;
+    }
+
+    @Override
+    public void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams) {
+        if (apiKey == null) {
+            return;
+        }
+        String value;
+        if (apiKeyPrefix != null) {
+            value = apiKeyPrefix + " " + apiKey;
+        } else {
+            value = apiKey;
+        }
+        if (location.equals("query")) {
+            queryParams.add(paramName, value);
+        } else if (location.equals("header")) {
+            headerParams.add(paramName, value);
+        } else if (location.equals("cookie")) {
+            cookieParams.add(paramName, value);
+        }
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/auth/Authentication.java

@@ -0,0 +1,29 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.auth;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.util.MultiValueMap;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public interface Authentication {
+    /**
+     * Apply authentication settings to header and / or query parameters.
+     *
+     * @param queryParams The query parameters for the request
+     * @param headerParams The header parameters for the request
+     * @param cookieParams The cookie parameters for the request
+     */
+    void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams);
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/auth/HttpBasicAuth.java

@@ -0,0 +1,51 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.auth;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Base64;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.util.MultiValueMap;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class HttpBasicAuth implements Authentication {
+    private String username;
+    private String password;
+
+    public String getUsername() {
+        return username;
+    }
+
+    public void setUsername(String username) {
+        this.username = username;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public void setPassword(String password) {
+        this.password = password;
+    }
+
+    @Override
+    public void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams) {
+        if (username == null && password == null) {
+            return;
+        }
+        String str = (username == null ? "" : username) + ":" + (password == null ? "" : password);
+        headerParams.add(HttpHeaders.AUTHORIZATION, "Basic " + Base64.getEncoder().encodeToString(str.getBytes(StandardCharsets.UTF_8)));
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/auth/HttpBearerAuth.java

@@ -0,0 +1,69 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.auth;
+
+import java.util.Optional;
+import java.util.function.Supplier;
+import org.springframework.http.HttpHeaders;
+import org.springframework.util.MultiValueMap;
+
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class HttpBearerAuth implements Authentication {
+    private final String scheme;
+    private Supplier<String> tokenSupplier;
+
+    public HttpBearerAuth(String scheme) {
+        this.scheme = scheme;
+    }
+
+    /**
+     * Gets the token, which together with the scheme, will be sent as the value of the Authorization header.
+     *
+     * @return The bearer token
+     */
+    public String getBearerToken() {
+        return tokenSupplier.get();
+    }
+
+    /**
+     * Sets the token, which together with the scheme, will be sent as the value of the Authorization header.
+     *
+     * @param bearerToken The bearer token to send in the Authorization header
+     */
+    public void setBearerToken(String bearerToken) {
+        this.tokenSupplier = () -> bearerToken;
+    }
+
+    /**
+     * Sets the supplier of tokens, which together with the scheme, will be sent as the value of the Authorization header.
+     *
+     * @param tokenSupplier The supplier of bearer tokens to send in the Authorization header
+     */
+    public void setBearerToken(Supplier<String> tokenSupplier) {
+        this.tokenSupplier = tokenSupplier;
+    }
+
+    @Override
+    public void applyToParams(MultiValueMap<String, String> queryParams, HttpHeaders headerParams, MultiValueMap<String, String> cookieParams) {
+        String bearerToken = Optional.ofNullable(tokenSupplier).map(Supplier::get).orElse(null);
+        if (bearerToken == null) {
+            return;
+        }
+        headerParams.add(HttpHeaders.AUTHORIZATION, (scheme != null ? upperCaseBearer(scheme) + " " : "") + bearerToken);
+    }
+
+    private static String upperCaseBearer(String scheme) {
+        return ("bearer".equalsIgnoreCase(scheme)) ? "Bearer" : scheme;
+    }
+}

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/model/DataChannel.java

@@ -0,0 +1,63 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import java.util.Objects;
+import java.util.Arrays;
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonValue;
+
+/**
+ * The transport-channel
+ */
+public enum DataChannel {
+  
+  BIKE("BIKE"),
+  
+  CAR("CAR"),
+  
+  BUS("BUS"),
+  
+  PLANE("PLANE");
+
+  private String value;
+
+  DataChannel(String value) {
+    this.value = value;
+  }
+
+  @JsonValue
+  public String getValue() {
+    return value;
+  }
+
+  @Override
+  public String toString() {
+    return String.valueOf(value);
+  }
+
+  @JsonCreator
+  public static DataChannel fromValue(String value) {
+    for (DataChannel b : DataChannel.values()) {
+      if (b.value.equals(value)) {
+        return b;
+      }
+    }
+    throw new IllegalArgumentException("Unexpected value '" + value + "'");
+  }
+}
+

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/model/DataDirection.java

@@ -0,0 +1,59 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import java.util.Objects;
+import java.util.Arrays;
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonValue;
+
+/**
+ * The direction a message travels
+ */
+public enum DataDirection {
+  
+  INGOING("INGOING"),
+  
+  OUTGOING("OUTGOING");
+
+  private String value;
+
+  DataDirection(String value) {
+    this.value = value;
+  }
+
+  @JsonValue
+  public String getValue() {
+    return value;
+  }
+
+  @Override
+  public String toString() {
+    return String.valueOf(value);
+  }
+
+  @JsonCreator
+  public static DataDirection fromValue(String value) {
+    for (DataDirection b : DataDirection.values()) {
+      if (b.value.equals(value)) {
+        return b;
+      }
+    }
+    throw new IllegalArgumentException("Unexpected value '" + value + "'");
+  }
+}
+

samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/model/InlineObject.java

@@ -0,0 +1,107 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import java.util.Objects;
+import java.util.Arrays;
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+import com.fasterxml.jackson.annotation.JsonValue;
+import java.util.UUID;
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+
+/**
+ * InlineObject
+ */
+@JsonPropertyOrder({
+  InlineObject.JSON_PROPERTY_MESSAGE_ID
+})
+@JsonTypeName("inline_object")
+@jakarta.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", comments = "Generator version: 7.14.0-SNAPSHOT")
+public class InlineObject {
+  public static final String JSON_PROPERTY_MESSAGE_ID = "messageId";
+  @jakarta.annotation.Nonnull
+  private UUID messageId;
+
+  public InlineObject() {
+  }
+
+  public InlineObject messageId(@jakarta.annotation.Nonnull UUID messageId) {
+    
+    this.messageId = messageId;
+    return this;
+  }
+
+  /**
+   * The messageID
+   * @return messageId
+   */
+  @jakarta.annotation.Nonnull
+  @JsonProperty(JSON_PROPERTY_MESSAGE_ID)
+  @JsonInclude(value = JsonInclude.Include.ALWAYS)
+
+  public UUID getMessageId() {
+    return messageId;
+  }
+
+
+  @JsonProperty(JSON_PROPERTY_MESSAGE_ID)
+  @JsonInclude(value = JsonInclude.Include.ALWAYS)
+  public void setMessageId(@jakarta.annotation.Nonnull UUID messageId) {
+    this.messageId = messageId;
+  }
+
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    InlineObject inlineObject = (InlineObject) o;
+    return Objects.equals(this.messageId, inlineObject.messageId);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(messageId);
+  }
+
+  @Override
+  public String toString() {
+    StringBuilder sb = new StringBuilder();
+    sb.append("class InlineObject {\n");
+    sb.append("    messageId: ").append(toIndentedString(messageId)).append("\n");
+    sb.append("}");
+    return sb.toString();
+  }
+
+  /**
+   * Convert the given object to string with each line indented by 4 spaces
+   * (except the first line).
+   */
+  private String toIndentedString(Object o) {
+    if (o == null) {
+      return "null";
+    }
+    return o.toString().replace("\n", "\n    ");
+  }
+
+}
+

samples/client/others/java/restclient-enum-in-multipart/src/test/java/org/openapitools/client/api/BasApiTest.java

@@ -0,0 +1,57 @@
+package org.openapitools.client.api;
+
+import java.io.File;
+import org.junit.jupiter.api.Test;
+
+import org.openapitools.client.model.DataChannel;
+import org.openapitools.client.model.DataDirection;
+
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+import org.openapitools.client.ApiClient;
+import java.nio.charset.StandardCharsets;
+import java.util.UUID;
+import org.springframework.web.client.RestClient;
+import org.springframework.core.io.AbstractResource;
+import org.springframework.core.io.FileSystemResource;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class BasApiTest {
+
+    @Test
+    public void requestTest() {
+
+        RestClient restClient = RestClient.builder() //
+                .requestInterceptor(
+                        (request, body, execution) -> {
+                            if (body != null && body.length > 0) {
+                                String bodyString = new String(body, StandardCharsets.UTF_8);
+                                bodyString = bodyString.replace("\r", "").replace("\n", "");
+                                String expected = "Content-Disposition: form-data; name=\"dataChannel\"Content-Type: text/plain;charset=UTF-8";
+                                assertTrue(bodyString.contains(expected));
+                            }
+                            return execution.execute(request, body);
+                        })
+                .build();
+
+        ApiClient apiClient = new ApiClient(restClient);
+        apiClient.setBasePath("http://localhost:8080");
+        apiClient.setUsername("user");
+        apiClient.setPassword("password");
+        BasApi basApi = new BasApi(apiClient);
+
+        File fileContent = new File("src/test/resources/testdata.xml");
+        String idempotencyKey = UUID.randomUUID().toString();
+        DataDirection dataDirection = DataDirection.INGOING;
+        DataChannel dataChannel = DataChannel.BIKE;
+        try {
+            basApi.createMessage(fileContent, idempotencyKey, dataDirection, dataChannel);
+        } catch (Exception e) {
+            // Will happen as we can´t use endpoint
+        }
+
+    }
+
+}

samples/client/others/java/restclient-enum-in-multipart/src/test/java/org/openapitools/client/model/DataChannelTest.java

@@ -0,0 +1,32 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for DataChannel
+ */
+class DataChannelTest {
+    /**
+     * Model tests for DataChannel
+     */
+    @Test
+    void testDataChannel() {
+        // TODO: test DataChannel
+    }
+
+}

samples/client/others/java/restclient-enum-in-multipart/src/test/java/org/openapitools/client/model/DataDirectionTest.java

@@ -0,0 +1,32 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for DataDirection
+ */
+class DataDirectionTest {
+    /**
+     * Model tests for DataDirection
+     */
+    @Test
+    void testDataDirection() {
+        // TODO: test DataDirection
+    }
+
+}

samples/client/others/java/restclient-enum-in-multipart/src/test/java/org/openapitools/client/model/InlineObjectTest.java

@@ -0,0 +1,48 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client.model;
+
+import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+import com.fasterxml.jackson.annotation.JsonValue;
+import java.util.UUID;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Model tests for InlineObject
+ */
+class InlineObjectTest {
+    private final InlineObject model = new InlineObject();
+
+    /**
+     * Model tests for InlineObject
+     */
+    @Test
+    void testInlineObject() {
+        // TODO: test InlineObject
+    }
+
+    /**
+     * Test the property 'messageId'
+     */
+    @Test
+    void messageIdTest() {
+        // TODO: test messageId
+    }
+
+}

samples/client/others/java/restclient-enum-in-multipart/src/test/resources/testdata.xml

@@ -0,0 +1,5 @@
+<xml>
+    <foo>
+        <name>Boo</name>
+    </foo>
+</xml>

samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java

@@ -637,6 +637,18 @@ public class ApiClient extends JavaTimeFormatter {
         addCookiesToRequest(cookieParams, requestBuilder);
         addCookiesToRequest(defaultCookies, requestBuilder);
 
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
         var selectedBody = selectBody(body, formParams, contentType);
         if (selectedBody != null) {
           requestBuilder.body(selectedBody);

samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java

@@ -637,6 +637,18 @@ public class ApiClient extends JavaTimeFormatter {
         addCookiesToRequest(cookieParams, requestBuilder);
         addCookiesToRequest(defaultCookies, requestBuilder);
 
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
         var selectedBody = selectBody(body, formParams, contentType);
         if (selectedBody != null) {
           requestBuilder.body(selectedBody);

samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java

@@ -657,6 +657,18 @@ public class ApiClient extends JavaTimeFormatter {
         addCookiesToRequest(cookieParams, requestBuilder);
         addCookiesToRequest(defaultCookies, requestBuilder);
 
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
         var selectedBody = selectBody(body, formParams, contentType);
         if (selectedBody != null) {
           requestBuilder.body(selectedBody);

samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ApiClient.java

@@ -657,6 +657,18 @@ public class ApiClient extends JavaTimeFormatter {
         addCookiesToRequest(cookieParams, requestBuilder);
         addCookiesToRequest(defaultCookies, requestBuilder);
 
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
         var selectedBody = selectBody(body, formParams, contentType);
         if (selectedBody != null) {
           requestBuilder.body(selectedBody);

samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java

@@ -657,6 +657,18 @@ public class ApiClient extends JavaTimeFormatter {
         addCookiesToRequest(cookieParams, requestBuilder);
         addCookiesToRequest(defaultCookies, requestBuilder);
 
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
         var selectedBody = selectBody(body, formParams, contentType);
         if (selectedBody != null) {
           requestBuilder.body(selectedBody);

samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ApiClient.java

@@ -657,6 +657,18 @@ public class ApiClient extends JavaTimeFormatter {
         addCookiesToRequest(cookieParams, requestBuilder);
         addCookiesToRequest(defaultCookies, requestBuilder);
 
+        if (MediaType.MULTIPART_FORM_DATA.isCompatibleWith(contentType)) {
+            formParams.forEach(
+                    (k, v) -> {
+                        if (v instanceof java.util.ArrayList) {
+                            Object o = v.get(0);
+                            if (o != null && o.getClass().getEnumConstants() != null) {
+                                v.set(0, o.toString());
+                            }
+                        }
+                    });
+        }
+
         var selectedBody = selectBody(body, formParams, contentType);
         if (selectedBody != null) {
           requestBuilder.body(selectedBody);