From 7a369d3b02e83a7898251f7a8dbfcba9774459d1 Mon Sep 17 00:00:00 2001
From: Bruno Coelho <4brunu@users.noreply.github.com>
Date: Wed, 9 Oct 2019 09:38:07 +0100
Subject: [PATCH] [kotlin-client] Add support okhttp3 and Android 4.x (#4008)

* [kotlin] support okhttp3

* [kotlin] create okhttp3 sample

* [kotlin-client] rename HttpClient to HttpLibrary

* [kotlin] move okhttp 3 to library model

* [kotlin] fix okhttp3 version

* [kotlin] fix kotlin client jvm okhttp3

* [kotlin] fix wrong spacing in okhttp3 code

* [kotlin] update okhttp3 sample to use parcelize models

* [kotlin] readd jvm tag
---
 bin/kotlin-client-all.sh                      |   7 +
 bin/kotlin-client-okhttp3.sh                  |  34 ++
 .../languages/KotlinClientCodegen.java        |  25 +-
 .../kotlin-client/build.gradle.mustache       |   7 +-
 .../jvm/infrastructure/ApiClient.kt.mustache  |  59 ++-
 .../ResponseExtensions.kt.mustache            |   8 +-
 .../kotlin-okhttp3/.openapi-generator-ignore  |  23 +
 .../kotlin-okhttp3/.openapi-generator/VERSION |   1 +
 .../client/petstore/kotlin-okhttp3/README.md  |  90 ++++
 .../petstore/kotlin-okhttp3/build.gradle      |  37 ++
 .../kotlin-okhttp3/docs/ApiResponse.md        |  12 +
 .../petstore/kotlin-okhttp3/docs/Category.md  |  11 +
 .../petstore/kotlin-okhttp3/docs/Order.md     |  22 +
 .../petstore/kotlin-okhttp3/docs/Pet.md       |  22 +
 .../petstore/kotlin-okhttp3/docs/PetApi.md    | 405 ++++++++++++++++++
 .../petstore/kotlin-okhttp3/docs/StoreApi.md  | 196 +++++++++
 .../petstore/kotlin-okhttp3/docs/Tag.md       |  11 +
 .../petstore/kotlin-okhttp3/docs/User.md      |  17 +
 .../petstore/kotlin-okhttp3/docs/UserApi.md   | 376 ++++++++++++++++
 .../petstore/kotlin-okhttp3/settings.gradle   |   2 +
 .../org/openapitools/client/apis/PetApi.kt    | 280 ++++++++++++
 .../org/openapitools/client/apis/StoreApi.kt  | 152 +++++++
 .../org/openapitools/client/apis/UserApi.kt   | 273 ++++++++++++
 .../client/infrastructure/ApiAbstractions.kt  |  23 +
 .../client/infrastructure/ApiClient.kt        | 168 ++++++++
 .../ApiInfrastructureResponse.kt              |  40 ++
 .../infrastructure/ApplicationDelegates.kt    |  29 ++
 .../client/infrastructure/ByteArrayAdapter.kt |  12 +
 .../client/infrastructure/Errors.kt           |  42 ++
 .../client/infrastructure/LocalDateAdapter.kt |  19 +
 .../infrastructure/LocalDateTimeAdapter.kt    |  19 +
 .../client/infrastructure/RequestConfig.kt    |  16 +
 .../client/infrastructure/RequestMethod.kt    |   8 +
 .../infrastructure/ResponseExtensions.kt      |  23 +
 .../client/infrastructure/Serializer.kt       |  18 +
 .../client/infrastructure/UUIDAdapter.kt      |  13 +
 .../openapitools/client/models/ApiResponse.kt |  35 ++
 .../openapitools/client/models/Category.kt    |  32 ++
 .../org/openapitools/client/models/Order.kt   |  64 +++
 .../org/openapitools/client/models/Pet.kt     |  66 +++
 .../org/openapitools/client/models/Tag.kt     |  32 ++
 .../org/openapitools/client/models/User.kt    |  51 +++
 .../petstore/kotlin-string/build.gradle       |   2 +-
 .../petstore/kotlin-threetenbp/build.gradle   |   2 +-
 samples/client/petstore/kotlin/build.gradle   |   2 +-
 45 files changed, 2760 insertions(+), 26 deletions(-)
 create mode 100755 bin/kotlin-client-all.sh
 create mode 100755 bin/kotlin-client-okhttp3.sh
 create mode 100644 samples/client/petstore/kotlin-okhttp3/.openapi-generator-ignore
 create mode 100644 samples/client/petstore/kotlin-okhttp3/.openapi-generator/VERSION
 create mode 100644 samples/client/petstore/kotlin-okhttp3/README.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/build.gradle
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/ApiResponse.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/Category.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/Order.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/Pet.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/PetApi.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/StoreApi.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/Tag.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/User.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/docs/UserApi.md
 create mode 100644 samples/client/petstore/kotlin-okhttp3/settings.gradle
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiInfrastructureResponse.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApplicationDelegates.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ResponseExtensions.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/UUIDAdapter.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/ApiResponse.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Category.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Order.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Pet.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Tag.kt
 create mode 100644 samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/User.kt

diff --git a/bin/kotlin-client-all.sh b/bin/kotlin-client-all.sh
new file mode 100755
index 00000000000..e7b2114e665
--- /dev/null
+++ b/bin/kotlin-client-all.sh
@@ -0,0 +1,7 @@
+#!/bin/sh
+
+./bin/kotlin-client-okhttp3.sh
+./bin/kotlin-client-petstore-multiplatform.sh
+./bin/kotlin-client-petstore.sh
+./bin/kotlin-client-string.sh
+./bin/kotlin-client-threetenbp.sh
diff --git a/bin/kotlin-client-okhttp3.sh b/bin/kotlin-client-okhttp3.sh
new file mode 100755
index 00000000000..abc0b50669e
--- /dev/null
+++ b/bin/kotlin-client-okhttp3.sh
@@ -0,0 +1,34 @@
+#!/bin/sh
+
+SCRIPT="$0"
+echo "# START SCRIPT: $SCRIPT"
+
+while [ -h "$SCRIPT" ] ; do
+  ls=$(ls -ld "$SCRIPT")
+  link=$(expr "$ls" : '.*-> \(.*\)$')
+  if expr "$link" : '/.*' > /dev/null; then
+    SCRIPT="$link"
+  else
+    SCRIPT=$(dirname "$SCRIPT")/"$link"
+  fi
+done
+
+if [ ! -d "${APP_DIR}" ]; then
+  APP_DIR=$(dirname "$SCRIPT")/..
+  APP_DIR=$(cd "${APP_DIR}"; pwd)
+fi
+
+executable="./modules/openapi-generator-cli/target/openapi-generator-cli.jar"
+
+if [ ! -f "$executable" ]
+then
+  mvn -B clean package
+fi
+
+# if you've executed sbt assembly previously it will use that instead.
+export JAVA_OPTS="${JAVA_OPTS} -Xmx1024M -DloggerPath=conf/log4j.properties"
+ags="generate -t modules/openapi-generator/src/main/resources/kotlin-client -i modules/openapi-generator/src/test/resources/2_0/petstore.yaml -g kotlin --artifact-id kotlin-petstore-okhttp3 --library jvm-okhttp3 --additional-properties parcelizeModels=true -o samples/client/petstore/kotlin-okhttp3 $@"
+
+java ${JAVA_OPTS} -jar ${executable} ${ags}
+
+cp CI/samples.ci/client/petstore/kotlin-okhttp3/pom.xml samples/client/petstore/kotlin-okhttp3/pom.xml
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
index 0543ff391eb..4f41bf090bc 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinClientCodegen.java
@@ -31,6 +31,8 @@ import java.util.Map;
 public class KotlinClientCodegen extends AbstractKotlinCodegen {
 
     protected static final String JVM = "jvm";
+    protected static final String JVM_OKHTTP4 = "jvm-okhttp4";
+    protected static final String JVM_OKHTTP3 = "jvm-okhttp3";
     protected static final String MULTIPLATFORM = "multiplatform";
 
     public static final String DATE_LIBRARY = "dateLibrary";
@@ -101,14 +103,15 @@ public class KotlinClientCodegen extends AbstractKotlinCodegen {
         collectionType.setDefault(this.collectionType);
         cliOptions.add(collectionType);
 
-        supportedLibraries.put(JVM, "Platform: Java Virtual Machine. HTTP client: OkHttp 2.7.5. JSON processing: Gson 2.8.1.");
+        supportedLibraries.put(JVM_OKHTTP4, "[DEFAULT] Platform: Java Virtual Machine. HTTP client: OkHttp 4.2.0 (Android 5.0+ and Java 8+). JSON processing: Moshi 1.8.0.");
+        supportedLibraries.put(JVM_OKHTTP3, "Platform: Java Virtual Machine. HTTP client: OkHttp 3.12.4 (Android 2.3+ and Java 7+). JSON processing: Moshi 1.8.0.");
         supportedLibraries.put(MULTIPLATFORM, "Platform: Kotlin multiplatform. HTTP client: Ktor 1.2.4. JSON processing: Kotlinx Serialization: 0.12.0.");
 
         CliOption libraryOption = new CliOption(CodegenConstants.LIBRARY, "Library template (sub-template) to use");
         libraryOption.setEnum(supportedLibraries);
-        libraryOption.setDefault(JVM);
+        libraryOption.setDefault(JVM_OKHTTP4);
         cliOptions.add(libraryOption);
-        setLibrary(JVM);
+        setLibrary(JVM_OKHTTP4);
     }
 
     public CodegenType getTag() {
@@ -156,8 +159,17 @@ public class KotlinClientCodegen extends AbstractKotlinCodegen {
         supportingFiles.add(new SupportingFile("infrastructure/RequestConfig.kt.mustache", infrastructureFolder, "RequestConfig.kt"));
         supportingFiles.add(new SupportingFile("infrastructure/RequestMethod.kt.mustache", infrastructureFolder, "RequestMethod.kt"));
 
-        if (JVM.equals(getLibrary())) {
+        if (isJVMLibrary()) {
             additionalProperties.put(JVM, true);
+            
+            if (JVM_OKHTTP4.equals(getLibrary())) {
+                additionalProperties.put(JVM_OKHTTP4, true);
+            } else if (JVM_OKHTTP3.equals(getLibrary())) {
+                additionalProperties.put(JVM_OKHTTP3, true);
+            }
+
+            supportedLibraries.put(JVM, "A workaround to use the same template folder for both 'jvm-okhttp3' and 'jvm-okhttp4'.");
+            setLibrary(JVM);
 
             // jvm specific supporting files
             supportingFiles.add(new SupportingFile("infrastructure/ApplicationDelegates.kt.mustache", infrastructureFolder, "ApplicationDelegates.kt"));
@@ -234,6 +246,11 @@ public class KotlinClientCodegen extends AbstractKotlinCodegen {
             typeMapping.put("list", "kotlin.collections.List");
             additionalProperties.put("isList", true);
         }
+
+    }
+
+    private boolean isJVMLibrary() {
+        return getLibrary() != null && (getLibrary().contains(JVM_OKHTTP4) || getLibrary().contains(JVM_OKHTTP3));
     }
 
     @Override
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache
index e735dc05a20..89e0197f8f7 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache
@@ -35,7 +35,12 @@ dependencies {
     {{#gson}}
     implementation "com.google.code.gson:gson:2.8.5"
     {{/gson}}
-    compile "com.squareup.okhttp3:okhttp:4.0.1"
+    {{#jvm-okhttp3}}
+    compile "com.squareup.okhttp3:okhttp:3.12.4"
+    {{/jvm-okhttp3}}
+    {{#jvm-okhttp4}}
+    compile "com.squareup.okhttp3:okhttp:4.2.0"
+    {{/jvm-okhttp4}}
     {{#threetenbp}}
     compile "org.threeten:threetenbp:1.3.8"
     {{/threetenbp}}
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ApiClient.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ApiClient.kt.mustache
index 358128a7b50..53671eb5499 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ApiClient.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ApiClient.kt.mustache
@@ -2,12 +2,24 @@ package {{packageName}}.infrastructure
 
 import okhttp3.OkHttpClient
 import okhttp3.RequestBody
+{{#jvm-okhttp3}}
+import okhttp3.MediaType
+{{/jvm-okhttp3}}
+{{#jvm-okhttp4}}
 import okhttp3.RequestBody.Companion.asRequestBody
 import okhttp3.RequestBody.Companion.toRequestBody
+{{/jvm-okhttp4}}
 import okhttp3.FormBody
+{{#jvm-okhttp3}}
+import okhttp3.HttpUrl
+{{/jvm-okhttp3}}
+{{#jvm-okhttp4}}
 import okhttp3.HttpUrl.Companion.toHttpUrlOrNull
+{{/jvm-okhttp4}}
 import okhttp3.ResponseBody
+{{#jvm-okhttp4}}
 import okhttp3.MediaType.Companion.toMediaTypeOrNull
+{{/jvm-okhttp4}}
 import okhttp3.Request
 import java.io.File
 
@@ -38,9 +50,16 @@ open class ApiClient(val baseUrl: String) {
 
     protected inline fun <reified T> requestBody(content: T, mediaType: String = JsonMediaType): RequestBody =
         when {
+            {{#jvm-okhttp3}}
+            content is File -> RequestBody.create(
+                MediaType.parse(mediaType), content
+            )
+            {{/jvm-okhttp3}}
+            {{#jvm-okhttp4}}
             content is File -> content.asRequestBody(
                 mediaType.toMediaTypeOrNull()
             )
+            {{/jvm-okhttp4}}
             mediaType == FormDataMediaType || mediaType == FormUrlEncMediaType -> {
                 FormBody.Builder().apply {
                     // content's type *must* be Map<String, Any>
@@ -50,9 +69,16 @@ open class ApiClient(val baseUrl: String) {
                     }
                 }.build()
             }
+            {{#jvm-okhttp3}}
+            mediaType == JsonMediaType -> RequestBody.create(
+                MediaType.parse(mediaType), Serializer.moshi.adapter(T::class.java).toJson(content)
+            )
+            {{/jvm-okhttp3}}
+            {{#jvm-okhttp4}}
             mediaType == JsonMediaType -> Serializer.moshi.adapter(T::class.java).toJson(content).toRequestBody(
                 mediaType.toMediaTypeOrNull()
             )
+            {{/jvm-okhttp4}}
             mediaType == XmlMediaType -> throw UnsupportedOperationException("xml not currently supported.")
             // TODO: this should be extended with other serializers
             else -> throw UnsupportedOperationException("requestBody currently only supports JSON body and File body.")
@@ -123,7 +149,12 @@ open class ApiClient(val baseUrl: String) {
     {{/hasAuthMethods}}
 
     protected inline fun <reified T: Any?> request(requestConfig: RequestConfig, body : Any? = null): ApiInfrastructureResponse<T?> {
+        {{#jvm-okhttp3}}
+        val httpUrl = HttpUrl.parse(baseUrl) ?: throw IllegalStateException("baseUrl is invalid.")
+        {{/jvm-okhttp3}}
+        {{#jvm-okhttp4}}
         val httpUrl = baseUrl.toHttpUrlOrNull() ?: throw IllegalStateException("baseUrl is invalid.")
+        {{/jvm-okhttp4}}
         {{#hasAuthMethods}}
 
         // take authMethod from operation
@@ -178,29 +209,29 @@ open class ApiClient(val baseUrl: String) {
         // TODO: handle specific mapping types. e.g. Map<int, Class<?>>
         when {
             response.isRedirect -> return Redirection(
-                    response.code,
-                    response.headers.toMultimap()
+                    response.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}},
+                    response.headers{{#jvm-okhttp3}}(){{/jvm-okhttp3}}.toMultimap()
             )
             response.isInformational -> return Informational(
-                    response.message,
-                    response.code,
-                    response.headers.toMultimap()
+                    response.message{{#jvm-okhttp3}}(){{/jvm-okhttp3}},
+                    response.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}},
+                    response.headers{{#jvm-okhttp3}}(){{/jvm-okhttp3}}.toMultimap()
             )
             response.isSuccessful -> return Success(
-                    responseBody(response.body, accept),
-                    response.code,
-                    response.headers.toMultimap()
+                    responseBody(response.body{{#jvm-okhttp3}}(){{/jvm-okhttp3}}, accept),
+                    response.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}},
+                    response.headers{{#jvm-okhttp3}}(){{/jvm-okhttp3}}.toMultimap()
             )
             response.isClientError -> return ClientError(
-                    response.body?.string(),
-                    response.code,
-                    response.headers.toMultimap()
+                    response.body{{#jvm-okhttp3}}(){{/jvm-okhttp3}}?.string(),
+                    response.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}},
+                    response.headers{{#jvm-okhttp3}}(){{/jvm-okhttp3}}.toMultimap()
             )
             else -> return ServerError(
                     null,
-                    response.body?.string(),
-                    response.code,
-                    response.headers.toMultimap()
+                    response.body{{#jvm-okhttp3}}(){{/jvm-okhttp3}}?.string(),
+                    response.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}},
+                    response.headers{{#jvm-okhttp3}}(){{/jvm-okhttp3}}.toMultimap()
             )
         }
     }
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ResponseExtensions.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ResponseExtensions.kt.mustache
index 8dd89399837..e3fee7031a0 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ResponseExtensions.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm/infrastructure/ResponseExtensions.kt.mustache
@@ -5,19 +5,19 @@ import okhttp3.Response
 /**
  * Provides an extension to evaluation whether the response is a 1xx code
  */
-val Response.isInformational : Boolean get() = this.code in 100..199
+val Response.isInformational : Boolean get() = this.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}} in 100..199
 
 /**
  * Provides an extension to evaluation whether the response is a 3xx code
  */
-val Response.isRedirect : Boolean get() = this.code in 300..399
+val Response.isRedirect : Boolean get() = this.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}} in 300..399
 
 /**
  * Provides an extension to evaluation whether the response is a 4xx code
  */
-val Response.isClientError : Boolean get() = this.code in 400..499
+val Response.isClientError : Boolean get() = this.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}} in 400..499
 
 /**
  * Provides an extension to evaluation whether the response is a 5xx (Standard) through 999 (non-standard) code
  */
-val Response.isServerError : Boolean get() = this.code in 500..999
\ No newline at end of file
+val Response.isServerError : Boolean get() = this.code{{#jvm-okhttp3}}(){{/jvm-okhttp3}} in 500..999
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/.openapi-generator-ignore b/samples/client/petstore/kotlin-okhttp3/.openapi-generator-ignore
new file mode 100644
index 00000000000..7484ee590a3
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/.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
diff --git a/samples/client/petstore/kotlin-okhttp3/.openapi-generator/VERSION b/samples/client/petstore/kotlin-okhttp3/.openapi-generator/VERSION
new file mode 100644
index 00000000000..0e97bd19efb
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/.openapi-generator/VERSION
@@ -0,0 +1 @@
+4.1.3-SNAPSHOT
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/README.md b/samples/client/petstore/kotlin-okhttp3/README.md
new file mode 100644
index 00000000000..aef4ea15bee
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/README.md
@@ -0,0 +1,90 @@
+# org.openapitools.client - Kotlin client library for OpenAPI Petstore
+
+## Requires
+
+* Kotlin 1.3.41
+* Gradle 4.9
+
+## Build
+
+First, create the gradle wrapper script:
+
+```
+gradle wrapper
+```
+
+Then, run:
+
+```
+./gradlew check assemble
+```
+
+This runs all tests and packages the library.
+
+## Features/Implementation Notes
+
+* Supports JSON inputs/outputs, File inputs, and Form inputs.
+* Supports collection formats for query parameters: csv, tsv, ssv, pipes.
+* Some Kotlin and Java types are fully qualified to avoid conflicts with types defined in OpenAPI definitions.
+* Implementation of ApiClient is intended to reduce method counts, specifically to benefit Android targets.
+
+<a name="documentation-for-api-endpoints"></a>
+## Documentation for API Endpoints
+
+All URIs are relative to *http://petstore.swagger.io/v2*
+
+Class | Method | HTTP request | Description
+------------ | ------------- | ------------- | -------------
+*PetApi* | [**addPet**](docs/PetApi.md#addpet) | **POST** /pet | Add a new pet to the store
+*PetApi* | [**deletePet**](docs/PetApi.md#deletepet) | **DELETE** /pet/{petId} | Deletes a pet
+*PetApi* | [**findPetsByStatus**](docs/PetApi.md#findpetsbystatus) | **GET** /pet/findByStatus | Finds Pets by status
+*PetApi* | [**findPetsByTags**](docs/PetApi.md#findpetsbytags) | **GET** /pet/findByTags | Finds Pets by tags
+*PetApi* | [**getPetById**](docs/PetApi.md#getpetbyid) | **GET** /pet/{petId} | Find pet by ID
+*PetApi* | [**updatePet**](docs/PetApi.md#updatepet) | **PUT** /pet | Update an existing pet
+*PetApi* | [**updatePetWithForm**](docs/PetApi.md#updatepetwithform) | **POST** /pet/{petId} | Updates a pet in the store with form data
+*PetApi* | [**uploadFile**](docs/PetApi.md#uploadfile) | **POST** /pet/{petId}/uploadImage | uploads an image
+*StoreApi* | [**deleteOrder**](docs/StoreApi.md#deleteorder) | **DELETE** /store/order/{orderId} | Delete purchase order by ID
+*StoreApi* | [**getInventory**](docs/StoreApi.md#getinventory) | **GET** /store/inventory | Returns pet inventories by status
+*StoreApi* | [**getOrderById**](docs/StoreApi.md#getorderbyid) | **GET** /store/order/{orderId} | Find purchase order by ID
+*StoreApi* | [**placeOrder**](docs/StoreApi.md#placeorder) | **POST** /store/order | Place an order for a pet
+*UserApi* | [**createUser**](docs/UserApi.md#createuser) | **POST** /user | Create user
+*UserApi* | [**createUsersWithArrayInput**](docs/UserApi.md#createuserswitharrayinput) | **POST** /user/createWithArray | Creates list of users with given input array
+*UserApi* | [**createUsersWithListInput**](docs/UserApi.md#createuserswithlistinput) | **POST** /user/createWithList | Creates list of users with given input array
+*UserApi* | [**deleteUser**](docs/UserApi.md#deleteuser) | **DELETE** /user/{username} | Delete user
+*UserApi* | [**getUserByName**](docs/UserApi.md#getuserbyname) | **GET** /user/{username} | Get user by user name
+*UserApi* | [**loginUser**](docs/UserApi.md#loginuser) | **GET** /user/login | Logs user into the system
+*UserApi* | [**logoutUser**](docs/UserApi.md#logoutuser) | **GET** /user/logout | Logs out current logged in user session
+*UserApi* | [**updateUser**](docs/UserApi.md#updateuser) | **PUT** /user/{username} | Updated user
+
+
+<a name="documentation-for-models"></a>
+## Documentation for Models
+
+ - [org.openapitools.client.models.ApiResponse](docs/ApiResponse.md)
+ - [org.openapitools.client.models.Category](docs/Category.md)
+ - [org.openapitools.client.models.Order](docs/Order.md)
+ - [org.openapitools.client.models.Pet](docs/Pet.md)
+ - [org.openapitools.client.models.Tag](docs/Tag.md)
+ - [org.openapitools.client.models.User](docs/User.md)
+
+
+<a name="documentation-for-authorization"></a>
+## Documentation for Authorization
+
+<a name="api_key"></a>
+### api_key
+
+- **Type**: API key
+- **API key parameter name**: api_key
+- **Location**: HTTP header
+
+<a name="petstore_auth"></a>
+### petstore_auth
+
+- **Type**: OAuth
+- **Flow**: implicit
+- **Authorization URL**: http://petstore.swagger.io/api/oauth/dialog
+- **Scopes**: 
+  - write:pets: modify pets in your account
+  - read:pets: read your pets
+
diff --git a/samples/client/petstore/kotlin-okhttp3/build.gradle b/samples/client/petstore/kotlin-okhttp3/build.gradle
new file mode 100644
index 00000000000..c3a555eaaed
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/build.gradle
@@ -0,0 +1,37 @@
+group 'org.openapitools'
+version '1.0.0'
+
+wrapper {
+    gradleVersion = '4.9'
+    distributionUrl = "https://services.gradle.org/distributions/gradle-$gradleVersion-all.zip"
+}
+
+buildscript {
+    ext.kotlin_version = '1.3.41'
+
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+apply plugin: 'kotlin'
+
+repositories {
+    mavenCentral()
+}
+
+test {
+    useJUnitPlatform()
+}
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
+    compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
+    compile "com.squareup.moshi:moshi-kotlin:1.8.0"
+    compile "com.squareup.moshi:moshi-adapters:1.8.0"
+    compile "com.squareup.okhttp3:okhttp:3.12.4"
+    testImplementation "io.kotlintest:kotlintest-runner-junit5:3.1.0"
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/ApiResponse.md b/samples/client/petstore/kotlin-okhttp3/docs/ApiResponse.md
new file mode 100644
index 00000000000..6b4c6bf2779
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/ApiResponse.md
@@ -0,0 +1,12 @@
+
+# ApiResponse
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**code** | **kotlin.Int** |  |  [optional]
+**type** | **kotlin.String** |  |  [optional]
+**message** | **kotlin.String** |  |  [optional]
+
+
+
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/Category.md b/samples/client/petstore/kotlin-okhttp3/docs/Category.md
new file mode 100644
index 00000000000..2c28a670fc7
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/Category.md
@@ -0,0 +1,11 @@
+
+# Category
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**id** | **kotlin.Long** |  |  [optional]
+**name** | **kotlin.String** |  |  [optional]
+
+
+
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/Order.md b/samples/client/petstore/kotlin-okhttp3/docs/Order.md
new file mode 100644
index 00000000000..ef31dbf2f4f
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/Order.md
@@ -0,0 +1,22 @@
+
+# Order
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**id** | **kotlin.Long** |  |  [optional]
+**petId** | **kotlin.Long** |  |  [optional]
+**quantity** | **kotlin.Int** |  |  [optional]
+**shipDate** | [**java.time.LocalDateTime**](java.time.LocalDateTime.md) |  |  [optional]
+**status** | [**inline**](#StatusEnum) | Order Status |  [optional]
+**complete** | **kotlin.Boolean** |  |  [optional]
+
+
+<a name="StatusEnum"></a>
+## Enum: status
+Name | Value
+---- | -----
+status | placed, approved, delivered
+
+
+
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/Pet.md b/samples/client/petstore/kotlin-okhttp3/docs/Pet.md
new file mode 100644
index 00000000000..ec775600737
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/Pet.md
@@ -0,0 +1,22 @@
+
+# Pet
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**id** | **kotlin.Long** |  |  [optional]
+**category** | [**Category**](Category.md) |  |  [optional]
+**name** | **kotlin.String** |  | 
+**photoUrls** | **kotlin.Array&lt;kotlin.String&gt;** |  | 
+**tags** | [**kotlin.Array&lt;Tag&gt;**](Tag.md) |  |  [optional]
+**status** | [**inline**](#StatusEnum) | pet status in the store |  [optional]
+
+
+<a name="StatusEnum"></a>
+## Enum: status
+Name | Value
+---- | -----
+status | available, pending, sold
+
+
+
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/PetApi.md b/samples/client/petstore/kotlin-okhttp3/docs/PetApi.md
new file mode 100644
index 00000000000..ea93e174527
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/PetApi.md
@@ -0,0 +1,405 @@
+# PetApi
+
+All URIs are relative to *http://petstore.swagger.io/v2*
+
+Method | HTTP request | Description
+------------- | ------------- | -------------
+[**addPet**](PetApi.md#addPet) | **POST** /pet | Add a new pet to the store
+[**deletePet**](PetApi.md#deletePet) | **DELETE** /pet/{petId} | Deletes a pet
+[**findPetsByStatus**](PetApi.md#findPetsByStatus) | **GET** /pet/findByStatus | Finds Pets by status
+[**findPetsByTags**](PetApi.md#findPetsByTags) | **GET** /pet/findByTags | Finds Pets by tags
+[**getPetById**](PetApi.md#getPetById) | **GET** /pet/{petId} | Find pet by ID
+[**updatePet**](PetApi.md#updatePet) | **PUT** /pet | Update an existing pet
+[**updatePetWithForm**](PetApi.md#updatePetWithForm) | **POST** /pet/{petId} | Updates a pet in the store with form data
+[**uploadFile**](PetApi.md#uploadFile) | **POST** /pet/{petId}/uploadImage | uploads an image
+
+
+<a name="addPet"></a>
+# **addPet**
+> addPet(body)
+
+Add a new pet to the store
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = PetApi()
+val body : Pet =  // Pet | Pet object that needs to be added to the store
+try {
+    apiInstance.addPet(body)
+} catch (e: ClientException) {
+    println("4xx response calling PetApi#addPet")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling PetApi#addPet")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **body** | [**Pet**](Pet.md)| Pet object that needs to be added to the store |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+
+Configure petstore_auth:
+    ApiClient.accessToken = ""
+
+### HTTP request headers
+
+ - **Content-Type**: application/json, application/xml
+ - **Accept**: Not defined
+
+<a name="deletePet"></a>
+# **deletePet**
+> deletePet(petId, apiKey)
+
+Deletes a pet
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = PetApi()
+val petId : kotlin.Long = 789 // kotlin.Long | Pet id to delete
+val apiKey : kotlin.String = apiKey_example // kotlin.String | 
+try {
+    apiInstance.deletePet(petId, apiKey)
+} catch (e: ClientException) {
+    println("4xx response calling PetApi#deletePet")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling PetApi#deletePet")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **petId** | **kotlin.Long**| Pet id to delete |
+ **apiKey** | **kotlin.String**|  | [optional]
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+
+Configure petstore_auth:
+    ApiClient.accessToken = ""
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
+<a name="findPetsByStatus"></a>
+# **findPetsByStatus**
+> kotlin.Array&lt;Pet&gt; findPetsByStatus(status)
+
+Finds Pets by status
+
+Multiple status values can be provided with comma separated strings
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = PetApi()
+val status : kotlin.Array<kotlin.String> =  // kotlin.Array<kotlin.String> | Status values that need to be considered for filter
+try {
+    val result : kotlin.Array<Pet> = apiInstance.findPetsByStatus(status)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling PetApi#findPetsByStatus")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling PetApi#findPetsByStatus")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **status** | [**kotlin.Array&lt;kotlin.String&gt;**](kotlin.String.md)| Status values that need to be considered for filter | [enum: available, pending, sold]
+
+### Return type
+
+[**kotlin.Array&lt;Pet&gt;**](Pet.md)
+
+### Authorization
+
+
+Configure petstore_auth:
+    ApiClient.accessToken = ""
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/xml, application/json
+
+<a name="findPetsByTags"></a>
+# **findPetsByTags**
+> kotlin.Array&lt;Pet&gt; findPetsByTags(tags)
+
+Finds Pets by tags
+
+Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = PetApi()
+val tags : kotlin.Array<kotlin.String> =  // kotlin.Array<kotlin.String> | Tags to filter by
+try {
+    val result : kotlin.Array<Pet> = apiInstance.findPetsByTags(tags)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling PetApi#findPetsByTags")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling PetApi#findPetsByTags")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **tags** | [**kotlin.Array&lt;kotlin.String&gt;**](kotlin.String.md)| Tags to filter by |
+
+### Return type
+
+[**kotlin.Array&lt;Pet&gt;**](Pet.md)
+
+### Authorization
+
+
+Configure petstore_auth:
+    ApiClient.accessToken = ""
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/xml, application/json
+
+<a name="getPetById"></a>
+# **getPetById**
+> Pet getPetById(petId)
+
+Find pet by ID
+
+Returns a single pet
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = PetApi()
+val petId : kotlin.Long = 789 // kotlin.Long | ID of pet to return
+try {
+    val result : Pet = apiInstance.getPetById(petId)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling PetApi#getPetById")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling PetApi#getPetById")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **petId** | **kotlin.Long**| ID of pet to return |
+
+### Return type
+
+[**Pet**](Pet.md)
+
+### Authorization
+
+
+Configure api_key:
+    ApiClient.apiKey["api_key"] = ""
+    ApiClient.apiKeyPrefix["api_key"] = ""
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/xml, application/json
+
+<a name="updatePet"></a>
+# **updatePet**
+> updatePet(body)
+
+Update an existing pet
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = PetApi()
+val body : Pet =  // Pet | Pet object that needs to be added to the store
+try {
+    apiInstance.updatePet(body)
+} catch (e: ClientException) {
+    println("4xx response calling PetApi#updatePet")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling PetApi#updatePet")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **body** | [**Pet**](Pet.md)| Pet object that needs to be added to the store |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+
+Configure petstore_auth:
+    ApiClient.accessToken = ""
+
+### HTTP request headers
+
+ - **Content-Type**: application/json, application/xml
+ - **Accept**: Not defined
+
+<a name="updatePetWithForm"></a>
+# **updatePetWithForm**
+> updatePetWithForm(petId, name, status)
+
+Updates a pet in the store with form data
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = PetApi()
+val petId : kotlin.Long = 789 // kotlin.Long | ID of pet that needs to be updated
+val name : kotlin.String = name_example // kotlin.String | Updated name of the pet
+val status : kotlin.String = status_example // kotlin.String | Updated status of the pet
+try {
+    apiInstance.updatePetWithForm(petId, name, status)
+} catch (e: ClientException) {
+    println("4xx response calling PetApi#updatePetWithForm")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling PetApi#updatePetWithForm")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **petId** | **kotlin.Long**| ID of pet that needs to be updated |
+ **name** | **kotlin.String**| Updated name of the pet | [optional]
+ **status** | **kotlin.String**| Updated status of the pet | [optional]
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+
+Configure petstore_auth:
+    ApiClient.accessToken = ""
+
+### HTTP request headers
+
+ - **Content-Type**: application/x-www-form-urlencoded
+ - **Accept**: Not defined
+
+<a name="uploadFile"></a>
+# **uploadFile**
+> ApiResponse uploadFile(petId, additionalMetadata, file)
+
+uploads an image
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = PetApi()
+val petId : kotlin.Long = 789 // kotlin.Long | ID of pet to update
+val additionalMetadata : kotlin.String = additionalMetadata_example // kotlin.String | Additional data to pass to server
+val file : java.io.File = BINARY_DATA_HERE // java.io.File | file to upload
+try {
+    val result : ApiResponse = apiInstance.uploadFile(petId, additionalMetadata, file)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling PetApi#uploadFile")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling PetApi#uploadFile")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **petId** | **kotlin.Long**| ID of pet to update |
+ **additionalMetadata** | **kotlin.String**| Additional data to pass to server | [optional]
+ **file** | **java.io.File**| file to upload | [optional]
+
+### Return type
+
+[**ApiResponse**](ApiResponse.md)
+
+### Authorization
+
+
+Configure petstore_auth:
+    ApiClient.accessToken = ""
+
+### HTTP request headers
+
+ - **Content-Type**: multipart/form-data
+ - **Accept**: application/json
+
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/StoreApi.md b/samples/client/petstore/kotlin-okhttp3/docs/StoreApi.md
new file mode 100644
index 00000000000..f4986041af8
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/StoreApi.md
@@ -0,0 +1,196 @@
+# StoreApi
+
+All URIs are relative to *http://petstore.swagger.io/v2*
+
+Method | HTTP request | Description
+------------- | ------------- | -------------
+[**deleteOrder**](StoreApi.md#deleteOrder) | **DELETE** /store/order/{orderId} | Delete purchase order by ID
+[**getInventory**](StoreApi.md#getInventory) | **GET** /store/inventory | Returns pet inventories by status
+[**getOrderById**](StoreApi.md#getOrderById) | **GET** /store/order/{orderId} | Find purchase order by ID
+[**placeOrder**](StoreApi.md#placeOrder) | **POST** /store/order | Place an order for a pet
+
+
+<a name="deleteOrder"></a>
+# **deleteOrder**
+> deleteOrder(orderId)
+
+Delete purchase order by ID
+
+For valid response try integer IDs with value &lt; 1000. Anything above 1000 or nonintegers will generate API errors
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = StoreApi()
+val orderId : kotlin.String = orderId_example // kotlin.String | ID of the order that needs to be deleted
+try {
+    apiInstance.deleteOrder(orderId)
+} catch (e: ClientException) {
+    println("4xx response calling StoreApi#deleteOrder")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling StoreApi#deleteOrder")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **orderId** | **kotlin.String**| ID of the order that needs to be deleted |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
+<a name="getInventory"></a>
+# **getInventory**
+> kotlin.collections.Map&lt;kotlin.String, kotlin.Int&gt; getInventory()
+
+Returns pet inventories by status
+
+Returns a map of status codes to quantities
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = StoreApi()
+try {
+    val result : kotlin.collections.Map<kotlin.String, kotlin.Int> = apiInstance.getInventory()
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling StoreApi#getInventory")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling StoreApi#getInventory")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+This endpoint does not need any parameter.
+
+### Return type
+
+**kotlin.collections.Map&lt;kotlin.String, kotlin.Int&gt;**
+
+### Authorization
+
+
+Configure api_key:
+    ApiClient.apiKey["api_key"] = ""
+    ApiClient.apiKeyPrefix["api_key"] = ""
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/json
+
+<a name="getOrderById"></a>
+# **getOrderById**
+> Order getOrderById(orderId)
+
+Find purchase order by ID
+
+For valid response try integer IDs with value &lt;&#x3D; 5 or &gt; 10. Other values will generated exceptions
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = StoreApi()
+val orderId : kotlin.Long = 789 // kotlin.Long | ID of pet that needs to be fetched
+try {
+    val result : Order = apiInstance.getOrderById(orderId)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling StoreApi#getOrderById")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling StoreApi#getOrderById")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **orderId** | **kotlin.Long**| ID of pet that needs to be fetched |
+
+### Return type
+
+[**Order**](Order.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/xml, application/json
+
+<a name="placeOrder"></a>
+# **placeOrder**
+> Order placeOrder(body)
+
+Place an order for a pet
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = StoreApi()
+val body : Order =  // Order | order placed for purchasing the pet
+try {
+    val result : Order = apiInstance.placeOrder(body)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling StoreApi#placeOrder")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling StoreApi#placeOrder")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **body** | [**Order**](Order.md)| order placed for purchasing the pet |
+
+### Return type
+
+[**Order**](Order.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/xml, application/json
+
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/Tag.md b/samples/client/petstore/kotlin-okhttp3/docs/Tag.md
new file mode 100644
index 00000000000..60ce1bcdbad
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/Tag.md
@@ -0,0 +1,11 @@
+
+# Tag
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**id** | **kotlin.Long** |  |  [optional]
+**name** | **kotlin.String** |  |  [optional]
+
+
+
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/User.md b/samples/client/petstore/kotlin-okhttp3/docs/User.md
new file mode 100644
index 00000000000..e801729b5ed
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/User.md
@@ -0,0 +1,17 @@
+
+# User
+
+## Properties
+Name | Type | Description | Notes
+------------ | ------------- | ------------- | -------------
+**id** | **kotlin.Long** |  |  [optional]
+**username** | **kotlin.String** |  |  [optional]
+**firstName** | **kotlin.String** |  |  [optional]
+**lastName** | **kotlin.String** |  |  [optional]
+**email** | **kotlin.String** |  |  [optional]
+**password** | **kotlin.String** |  |  [optional]
+**phone** | **kotlin.String** |  |  [optional]
+**userStatus** | **kotlin.Int** | User Status |  [optional]
+
+
+
diff --git a/samples/client/petstore/kotlin-okhttp3/docs/UserApi.md b/samples/client/petstore/kotlin-okhttp3/docs/UserApi.md
new file mode 100644
index 00000000000..0f55f06bc62
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/docs/UserApi.md
@@ -0,0 +1,376 @@
+# UserApi
+
+All URIs are relative to *http://petstore.swagger.io/v2*
+
+Method | HTTP request | Description
+------------- | ------------- | -------------
+[**createUser**](UserApi.md#createUser) | **POST** /user | Create user
+[**createUsersWithArrayInput**](UserApi.md#createUsersWithArrayInput) | **POST** /user/createWithArray | Creates list of users with given input array
+[**createUsersWithListInput**](UserApi.md#createUsersWithListInput) | **POST** /user/createWithList | Creates list of users with given input array
+[**deleteUser**](UserApi.md#deleteUser) | **DELETE** /user/{username} | Delete user
+[**getUserByName**](UserApi.md#getUserByName) | **GET** /user/{username} | Get user by user name
+[**loginUser**](UserApi.md#loginUser) | **GET** /user/login | Logs user into the system
+[**logoutUser**](UserApi.md#logoutUser) | **GET** /user/logout | Logs out current logged in user session
+[**updateUser**](UserApi.md#updateUser) | **PUT** /user/{username} | Updated user
+
+
+<a name="createUser"></a>
+# **createUser**
+> createUser(body)
+
+Create user
+
+This can only be done by the logged in user.
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = UserApi()
+val body : User =  // User | Created user object
+try {
+    apiInstance.createUser(body)
+} catch (e: ClientException) {
+    println("4xx response calling UserApi#createUser")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling UserApi#createUser")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **body** | [**User**](User.md)| Created user object |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
+<a name="createUsersWithArrayInput"></a>
+# **createUsersWithArrayInput**
+> createUsersWithArrayInput(body)
+
+Creates list of users with given input array
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = UserApi()
+val body : kotlin.Array<User> =  // kotlin.Array<User> | List of user object
+try {
+    apiInstance.createUsersWithArrayInput(body)
+} catch (e: ClientException) {
+    println("4xx response calling UserApi#createUsersWithArrayInput")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling UserApi#createUsersWithArrayInput")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **body** | [**kotlin.Array&lt;User&gt;**](User.md)| List of user object |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
+<a name="createUsersWithListInput"></a>
+# **createUsersWithListInput**
+> createUsersWithListInput(body)
+
+Creates list of users with given input array
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = UserApi()
+val body : kotlin.Array<User> =  // kotlin.Array<User> | List of user object
+try {
+    apiInstance.createUsersWithListInput(body)
+} catch (e: ClientException) {
+    println("4xx response calling UserApi#createUsersWithListInput")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling UserApi#createUsersWithListInput")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **body** | [**kotlin.Array&lt;User&gt;**](User.md)| List of user object |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
+<a name="deleteUser"></a>
+# **deleteUser**
+> deleteUser(username)
+
+Delete user
+
+This can only be done by the logged in user.
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = UserApi()
+val username : kotlin.String = username_example // kotlin.String | The name that needs to be deleted
+try {
+    apiInstance.deleteUser(username)
+} catch (e: ClientException) {
+    println("4xx response calling UserApi#deleteUser")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling UserApi#deleteUser")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **username** | **kotlin.String**| The name that needs to be deleted |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
+<a name="getUserByName"></a>
+# **getUserByName**
+> User getUserByName(username)
+
+Get user by user name
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = UserApi()
+val username : kotlin.String = username_example // kotlin.String | The name that needs to be fetched. Use user1 for testing.
+try {
+    val result : User = apiInstance.getUserByName(username)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling UserApi#getUserByName")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling UserApi#getUserByName")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **username** | **kotlin.String**| The name that needs to be fetched. Use user1 for testing. |
+
+### Return type
+
+[**User**](User.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/xml, application/json
+
+<a name="loginUser"></a>
+# **loginUser**
+> kotlin.String loginUser(username, password)
+
+Logs user into the system
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = UserApi()
+val username : kotlin.String = username_example // kotlin.String | The user name for login
+val password : kotlin.String = password_example // kotlin.String | The password for login in clear text
+try {
+    val result : kotlin.String = apiInstance.loginUser(username, password)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling UserApi#loginUser")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling UserApi#loginUser")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **username** | **kotlin.String**| The user name for login |
+ **password** | **kotlin.String**| The password for login in clear text |
+
+### Return type
+
+**kotlin.String**
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: application/xml, application/json
+
+<a name="logoutUser"></a>
+# **logoutUser**
+> logoutUser()
+
+Logs out current logged in user session
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = UserApi()
+try {
+    apiInstance.logoutUser()
+} catch (e: ClientException) {
+    println("4xx response calling UserApi#logoutUser")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling UserApi#logoutUser")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+This endpoint does not need any parameter.
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
+<a name="updateUser"></a>
+# **updateUser**
+> updateUser(username, body)
+
+Updated user
+
+This can only be done by the logged in user.
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = UserApi()
+val username : kotlin.String = username_example // kotlin.String | name that need to be deleted
+val body : User =  // User | Updated user object
+try {
+    apiInstance.updateUser(username, body)
+} catch (e: ClientException) {
+    println("4xx response calling UserApi#updateUser")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling UserApi#updateUser")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **username** | **kotlin.String**| name that need to be deleted |
+ **body** | [**User**](User.md)| Updated user object |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
diff --git a/samples/client/petstore/kotlin-okhttp3/settings.gradle b/samples/client/petstore/kotlin-okhttp3/settings.gradle
new file mode 100644
index 00000000000..a18186278ec
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/settings.gradle
@@ -0,0 +1,2 @@
+
+rootProject.name = 'kotlin-petstore-okhttp3'
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
new file mode 100644
index 00000000000..15f63f2a1b5
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -0,0 +1,280 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.apis
+
+import org.openapitools.client.models.ApiResponse
+import org.openapitools.client.models.Pet
+
+import org.openapitools.client.infrastructure.ApiClient
+import org.openapitools.client.infrastructure.ClientException
+import org.openapitools.client.infrastructure.ClientError
+import org.openapitools.client.infrastructure.ServerException
+import org.openapitools.client.infrastructure.ServerError
+import org.openapitools.client.infrastructure.MultiValueMap
+import org.openapitools.client.infrastructure.RequestConfig
+import org.openapitools.client.infrastructure.RequestMethod
+import org.openapitools.client.infrastructure.ResponseType
+import org.openapitools.client.infrastructure.Success
+import org.openapitools.client.infrastructure.toMultiValue
+
+class PetApi(basePath: kotlin.String = "http://petstore.swagger.io/v2") : ApiClient(basePath) {
+
+    /**
+    * Add a new pet to the store
+    * 
+    * @param body Pet object that needs to be added to the store 
+    * @return void
+    */
+    fun addPet(body: Pet) : Unit {
+        val localVariableBody: kotlin.Any? = body
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.POST,
+            "/pet",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Deletes a pet
+    * 
+    * @param petId Pet id to delete 
+    * @param apiKey  (optional)
+    * @return void
+    */
+    fun deletePet(petId: kotlin.Long, apiKey: kotlin.String?) : Unit {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf("api_key" to apiKey.toString())
+        val localVariableConfig = RequestConfig(
+            RequestMethod.DELETE,
+            "/pet/{petId}".replace("{"+"petId"+"}", "$petId"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Finds Pets by status
+    * Multiple status values can be provided with comma separated strings
+    * @param status Status values that need to be considered for filter 
+    * @return kotlin.Array<Pet>
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun findPetsByStatus(status: kotlin.Array<kotlin.String>) : kotlin.Array<Pet> {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf("status" to toMultiValue(status.toList(), "csv"))
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.GET,
+            "/pet/findByStatus",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<kotlin.Array<Pet>>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as kotlin.Array<Pet>
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Finds Pets by tags
+    * Multiple tags can be provided with comma separated strings. Use tag1, tag2, tag3 for testing.
+    * @param tags Tags to filter by 
+    * @return kotlin.Array<Pet>
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun findPetsByTags(tags: kotlin.Array<kotlin.String>) : kotlin.Array<Pet> {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf("tags" to toMultiValue(tags.toList(), "csv"))
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.GET,
+            "/pet/findByTags",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<kotlin.Array<Pet>>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as kotlin.Array<Pet>
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Find pet by ID
+    * Returns a single pet
+    * @param petId ID of pet to return 
+    * @return Pet
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun getPetById(petId: kotlin.Long) : Pet {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.GET,
+            "/pet/{petId}".replace("{"+"petId"+"}", "$petId"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Pet>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as Pet
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Update an existing pet
+    * 
+    * @param body Pet object that needs to be added to the store 
+    * @return void
+    */
+    fun updatePet(body: Pet) : Unit {
+        val localVariableBody: kotlin.Any? = body
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.PUT,
+            "/pet",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Updates a pet in the store with form data
+    * 
+    * @param petId ID of pet that needs to be updated 
+    * @param name Updated name of the pet (optional)
+    * @param status Updated status of the pet (optional)
+    * @return void
+    */
+    fun updatePetWithForm(petId: kotlin.Long, name: kotlin.String?, status: kotlin.String?) : Unit {
+        val localVariableBody: kotlin.Any? = mapOf("name" to "$name", "status" to "$status")
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf("Content-Type" to "")
+        val localVariableConfig = RequestConfig(
+            RequestMethod.POST,
+            "/pet/{petId}".replace("{"+"petId"+"}", "$petId"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * uploads an image
+    * 
+    * @param petId ID of pet to update 
+    * @param additionalMetadata Additional data to pass to server (optional)
+    * @param file file to upload (optional)
+    * @return ApiResponse
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun uploadFile(petId: kotlin.Long, additionalMetadata: kotlin.String?, file: java.io.File?) : ApiResponse {
+        val localVariableBody: kotlin.Any? = mapOf("additionalMetadata" to "$additionalMetadata", "file" to "$file")
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf("Content-Type" to "")
+        val localVariableConfig = RequestConfig(
+            RequestMethod.POST,
+            "/pet/{petId}/uploadImage".replace("{"+"petId"+"}", "$petId"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<ApiResponse>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as ApiResponse
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
new file mode 100644
index 00000000000..90d681f8f34
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -0,0 +1,152 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.apis
+
+import org.openapitools.client.models.Order
+
+import org.openapitools.client.infrastructure.ApiClient
+import org.openapitools.client.infrastructure.ClientException
+import org.openapitools.client.infrastructure.ClientError
+import org.openapitools.client.infrastructure.ServerException
+import org.openapitools.client.infrastructure.ServerError
+import org.openapitools.client.infrastructure.MultiValueMap
+import org.openapitools.client.infrastructure.RequestConfig
+import org.openapitools.client.infrastructure.RequestMethod
+import org.openapitools.client.infrastructure.ResponseType
+import org.openapitools.client.infrastructure.Success
+import org.openapitools.client.infrastructure.toMultiValue
+
+class StoreApi(basePath: kotlin.String = "http://petstore.swagger.io/v2") : ApiClient(basePath) {
+
+    /**
+    * Delete purchase order by ID
+    * For valid response try integer IDs with value &lt; 1000. Anything above 1000 or nonintegers will generate API errors
+    * @param orderId ID of the order that needs to be deleted 
+    * @return void
+    */
+    fun deleteOrder(orderId: kotlin.String) : Unit {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.DELETE,
+            "/store/order/{orderId}".replace("{"+"orderId"+"}", "$orderId"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Returns pet inventories by status
+    * Returns a map of status codes to quantities
+    * @return kotlin.collections.Map<kotlin.String, kotlin.Int>
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun getInventory() : kotlin.collections.Map<kotlin.String, kotlin.Int> {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.GET,
+            "/store/inventory",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<kotlin.collections.Map<kotlin.String, kotlin.Int>>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as kotlin.collections.Map<kotlin.String, kotlin.Int>
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Find purchase order by ID
+    * For valid response try integer IDs with value &lt;&#x3D; 5 or &gt; 10. Other values will generated exceptions
+    * @param orderId ID of pet that needs to be fetched 
+    * @return Order
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun getOrderById(orderId: kotlin.Long) : Order {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.GET,
+            "/store/order/{orderId}".replace("{"+"orderId"+"}", "$orderId"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Order>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as Order
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Place an order for a pet
+    * 
+    * @param body order placed for purchasing the pet 
+    * @return Order
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun placeOrder(body: Order) : Order {
+        val localVariableBody: kotlin.Any? = body
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.POST,
+            "/store/order",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Order>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as Order
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
new file mode 100644
index 00000000000..daaaeae3150
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -0,0 +1,273 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.apis
+
+import org.openapitools.client.models.User
+
+import org.openapitools.client.infrastructure.ApiClient
+import org.openapitools.client.infrastructure.ClientException
+import org.openapitools.client.infrastructure.ClientError
+import org.openapitools.client.infrastructure.ServerException
+import org.openapitools.client.infrastructure.ServerError
+import org.openapitools.client.infrastructure.MultiValueMap
+import org.openapitools.client.infrastructure.RequestConfig
+import org.openapitools.client.infrastructure.RequestMethod
+import org.openapitools.client.infrastructure.ResponseType
+import org.openapitools.client.infrastructure.Success
+import org.openapitools.client.infrastructure.toMultiValue
+
+class UserApi(basePath: kotlin.String = "http://petstore.swagger.io/v2") : ApiClient(basePath) {
+
+    /**
+    * Create user
+    * This can only be done by the logged in user.
+    * @param body Created user object 
+    * @return void
+    */
+    fun createUser(body: User) : Unit {
+        val localVariableBody: kotlin.Any? = body
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.POST,
+            "/user",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Creates list of users with given input array
+    * 
+    * @param body List of user object 
+    * @return void
+    */
+    fun createUsersWithArrayInput(body: kotlin.Array<User>) : Unit {
+        val localVariableBody: kotlin.Any? = body
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.POST,
+            "/user/createWithArray",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Creates list of users with given input array
+    * 
+    * @param body List of user object 
+    * @return void
+    */
+    fun createUsersWithListInput(body: kotlin.Array<User>) : Unit {
+        val localVariableBody: kotlin.Any? = body
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.POST,
+            "/user/createWithList",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Delete user
+    * This can only be done by the logged in user.
+    * @param username The name that needs to be deleted 
+    * @return void
+    */
+    fun deleteUser(username: kotlin.String) : Unit {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.DELETE,
+            "/user/{username}".replace("{"+"username"+"}", "$username"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Get user by user name
+    * 
+    * @param username The name that needs to be fetched. Use user1 for testing. 
+    * @return User
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun getUserByName(username: kotlin.String) : User {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.GET,
+            "/user/{username}".replace("{"+"username"+"}", "$username"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<User>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as User
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Logs user into the system
+    * 
+    * @param username The user name for login 
+    * @param password The password for login in clear text 
+    * @return kotlin.String
+    */
+    @Suppress("UNCHECKED_CAST")
+    fun loginUser(username: kotlin.String, password: kotlin.String) : kotlin.String {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf("username" to listOf("$username"), "password" to listOf("$password"))
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.GET,
+            "/user/login",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<kotlin.String>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> (response as Success<*>).data as kotlin.String
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Logs out current logged in user session
+    * 
+    * @return void
+    */
+    fun logoutUser() : Unit {
+        val localVariableBody: kotlin.Any? = null
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.GET,
+            "/user/logout",
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+    /**
+    * Updated user
+    * This can only be done by the logged in user.
+    * @param username name that need to be deleted 
+    * @param body Updated user object 
+    * @return void
+    */
+    fun updateUser(username: kotlin.String, body: User) : Unit {
+        val localVariableBody: kotlin.Any? = body
+        val localVariableQuery: MultiValueMap = mapOf()
+        val localVariableHeaders: MutableMap<String, String> = mutableMapOf()
+        val localVariableConfig = RequestConfig(
+            RequestMethod.PUT,
+            "/user/{username}".replace("{"+"username"+"}", "$username"),
+            query = localVariableQuery,
+            headers = localVariableHeaders
+        )
+        val response = request<Any?>(
+            localVariableConfig,
+            localVariableBody
+        )
+
+        return when (response.responseType) {
+            ResponseType.Success -> Unit
+            ResponseType.Informational -> throw UnsupportedOperationException("Client does not support Informational responses.")
+            ResponseType.Redirection -> throw UnsupportedOperationException("Client does not support Redirection responses.")
+            ResponseType.ClientError -> throw ClientException((response as ClientError<*>).body as? String ?: "Client error")
+            ResponseType.ServerError -> throw ServerException((response as ServerError<*>).message ?: "Server error")
+        }
+    }
+
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt
new file mode 100644
index 00000000000..f97cb88d233
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt
@@ -0,0 +1,23 @@
+package org.openapitools.client.infrastructure
+
+typealias MultiValueMap = Map<String,List<String>>
+
+fun collectionDelimiter(collectionFormat: String) = when(collectionFormat) {
+    "csv" -> ","
+    "tsv" -> "\t"
+    "pipes" -> "|"
+    "ssv" -> " "
+    else -> ""
+}
+
+val defaultMultiValueConverter: (item: Any?) -> String = { item -> "$item" }
+
+fun <T : Any?> toMultiValue(items: Array<T>, collectionFormat: String, map: (item: T) -> String = defaultMultiValueConverter)
+        = toMultiValue(items.asIterable(), collectionFormat, map)
+
+fun <T : Any?> toMultiValue(items: Iterable<T>, collectionFormat: String, map: (item: T) -> String = defaultMultiValueConverter): List<String> {
+    return when(collectionFormat) {
+        "multi" -> items.map(map)
+        else -> listOf(items.joinToString(separator = collectionDelimiter(collectionFormat), transform = map))
+    }
+}
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
new file mode 100644
index 00000000000..5b4056205eb
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -0,0 +1,168 @@
+package org.openapitools.client.infrastructure
+
+import okhttp3.OkHttpClient
+import okhttp3.RequestBody
+import okhttp3.MediaType
+import okhttp3.FormBody
+import okhttp3.HttpUrl
+import okhttp3.ResponseBody
+import okhttp3.Request
+import java.io.File
+
+open class ApiClient(val baseUrl: String) {
+    companion object {
+        protected const val ContentType = "Content-Type"
+        protected const val Accept = "Accept"
+        protected const val Authorization = "Authorization"
+        protected const val JsonMediaType = "application/json"
+        protected const val FormDataMediaType = "multipart/form-data"
+        protected const val FormUrlEncMediaType = "application/x-www-form-urlencoded"
+        protected const val XmlMediaType = "application/xml"
+
+        val apiKey: MutableMap<String, String> = mutableMapOf()
+        val apiKeyPrefix: MutableMap<String, String> = mutableMapOf()
+        var username: String? = null
+        var password: String? = null
+        var accessToken: String? = null
+
+        @JvmStatic
+        val client: OkHttpClient by lazy {
+            builder.build()
+        }
+
+        @JvmStatic
+        val builder: OkHttpClient.Builder = OkHttpClient.Builder()
+    }
+
+    protected inline fun <reified T> requestBody(content: T, mediaType: String = JsonMediaType): RequestBody =
+        when {
+            content is File -> RequestBody.create(
+                MediaType.parse(mediaType), content
+            )
+            mediaType == FormDataMediaType || mediaType == FormUrlEncMediaType -> {
+                FormBody.Builder().apply {
+                    // content's type *must* be Map<String, Any>
+                    @Suppress("UNCHECKED_CAST")
+                    (content as Map<String,String>).forEach { (key, value) ->
+                        add(key, value)
+                    }
+                }.build()
+            }
+            mediaType == JsonMediaType -> RequestBody.create(
+                MediaType.parse(mediaType), Serializer.moshi.adapter(T::class.java).toJson(content)
+            )
+            mediaType == XmlMediaType -> throw UnsupportedOperationException("xml not currently supported.")
+            // TODO: this should be extended with other serializers
+            else -> throw UnsupportedOperationException("requestBody currently only supports JSON body and File body.")
+        }
+
+    protected inline fun <reified T: Any?> responseBody(body: ResponseBody?, mediaType: String? = JsonMediaType): T? {
+        if(body == null) {
+            return null
+        }
+        val bodyContent = body.string()
+        if (bodyContent.isEmpty()) {
+            return null
+        }
+        return when(mediaType) {
+            JsonMediaType -> Serializer.moshi.adapter(T::class.java).fromJson(bodyContent)
+            else ->  throw UnsupportedOperationException("responseBody currently only supports JSON body.")
+        }
+    }
+
+    protected fun updateAuthParams(requestConfig: RequestConfig) {
+        if (requestConfig.headers["api_key"].isNullOrEmpty()) {
+            if (apiKey["api_key"] != null) {
+                if (apiKeyPrefix["api_key"] != null) {
+                    requestConfig.headers["api_key"] = apiKeyPrefix["api_key"]!! + " " + apiKey["api_key"]!!
+                } else {
+                    requestConfig.headers["api_key"] = apiKey["api_key"]!!
+                }
+            }
+        }
+        if (requestConfig.headers[Authorization].isNullOrEmpty()) {
+            requestConfig.headers[Authorization] = "Bearer " + accessToken
+        }
+    }
+
+    protected inline fun <reified T: Any?> request(requestConfig: RequestConfig, body : Any? = null): ApiInfrastructureResponse<T?> {
+        val httpUrl = HttpUrl.parse(baseUrl) ?: throw IllegalStateException("baseUrl is invalid.")
+
+        // take authMethod from operation
+        updateAuthParams(requestConfig)
+
+        val url = httpUrl.newBuilder()
+            .addPathSegments(requestConfig.path.trimStart('/'))
+            .apply {
+                requestConfig.query.forEach { query ->
+                    query.value.forEach { queryValue ->
+                        addQueryParameter(query.key, queryValue)
+                    }
+                }
+            }.build()
+
+        // take content-type/accept from spec or set to default (application/json) if not defined
+        if (requestConfig.headers[ContentType].isNullOrEmpty()) {
+            requestConfig.headers[ContentType] = JsonMediaType
+        }
+        if (requestConfig.headers[Accept].isNullOrEmpty()) {
+            requestConfig.headers[Accept] = JsonMediaType
+        }
+        val headers = requestConfig.headers
+
+        if(headers[ContentType] ?: "" == "") {
+            throw kotlin.IllegalStateException("Missing Content-Type header. This is required.")
+        }
+
+        if(headers[Accept] ?: "" == "") {
+            throw kotlin.IllegalStateException("Missing Accept header. This is required.")
+        }
+
+        // TODO: support multiple contentType options here.
+        val contentType = (headers[ContentType] as String).substringBefore(";").toLowerCase()
+
+        val request = when (requestConfig.method) {
+            RequestMethod.DELETE -> Request.Builder().url(url).delete()
+            RequestMethod.GET -> Request.Builder().url(url)
+            RequestMethod.HEAD -> Request.Builder().url(url).head()
+            RequestMethod.PATCH -> Request.Builder().url(url).patch(requestBody(body, contentType))
+            RequestMethod.PUT -> Request.Builder().url(url).put(requestBody(body, contentType))
+            RequestMethod.POST -> Request.Builder().url(url).post(requestBody(body, contentType))
+            RequestMethod.OPTIONS -> Request.Builder().url(url).method("OPTIONS", null)
+        }.apply {
+            headers.forEach { header -> addHeader(header.key, header.value) }
+        }.build()
+
+        val response = client.newCall(request).execute()
+        val accept = response.header(ContentType)?.substringBefore(";")?.toLowerCase()
+
+        // TODO: handle specific mapping types. e.g. Map<int, Class<?>>
+        when {
+            response.isRedirect -> return Redirection(
+                    response.code(),
+                    response.headers().toMultimap()
+            )
+            response.isInformational -> return Informational(
+                    response.message(),
+                    response.code(),
+                    response.headers().toMultimap()
+            )
+            response.isSuccessful -> return Success(
+                    responseBody(response.body(), accept),
+                    response.code(),
+                    response.headers().toMultimap()
+            )
+            response.isClientError -> return ClientError(
+                    response.body()?.string(),
+                    response.code(),
+                    response.headers().toMultimap()
+            )
+            else -> return ServerError(
+                    null,
+                    response.body()?.string(),
+                    response.code(),
+                    response.headers().toMultimap()
+            )
+        }
+    }
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiInfrastructureResponse.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiInfrastructureResponse.kt
new file mode 100644
index 00000000000..f1a8aecc914
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApiInfrastructureResponse.kt
@@ -0,0 +1,40 @@
+package org.openapitools.client.infrastructure
+
+enum class ResponseType {
+    Success, Informational, Redirection, ClientError, ServerError
+}
+
+abstract class ApiInfrastructureResponse<T>(val responseType: ResponseType) {
+    abstract val statusCode: Int
+    abstract val headers: Map<String,List<String>>
+}
+
+class Success<T>(
+    val data: T,
+    override val statusCode: Int = -1,
+    override val headers: Map<String, List<String>> = mapOf()
+): ApiInfrastructureResponse<T>(ResponseType.Success)
+
+class Informational<T>(
+    val statusText: String,
+    override val statusCode: Int = -1,
+    override val headers: Map<String, List<String>> = mapOf()
+) : ApiInfrastructureResponse<T>(ResponseType.Informational)
+
+class Redirection<T>(
+    override val statusCode: Int = -1,
+    override val headers: Map<String, List<String>> = mapOf()
+) : ApiInfrastructureResponse<T>(ResponseType.Redirection)
+
+class ClientError<T>(
+    val body: Any? = null,
+    override val statusCode: Int = -1,
+    override val headers: Map<String, List<String>> = mapOf()
+) : ApiInfrastructureResponse<T>(ResponseType.ClientError)
+
+class ServerError<T>(
+    val message: String? = null,
+    val body: Any? = null,
+    override val statusCode: Int = -1,
+    override val headers: Map<String, List<String>>
+): ApiInfrastructureResponse<T>(ResponseType.ServerError)
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApplicationDelegates.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApplicationDelegates.kt
new file mode 100644
index 00000000000..dd34bd48b2c
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ApplicationDelegates.kt
@@ -0,0 +1,29 @@
+package org.openapitools.client.infrastructure
+
+import kotlin.properties.ReadWriteProperty
+import kotlin.reflect.KProperty
+
+object ApplicationDelegates {
+    /**
+     * Provides a property delegate, allowing the property to be set once and only once.
+     *
+     * If unset (no default value), a get on the property will throw [IllegalStateException].
+     */
+    fun <T> setOnce(defaultValue: T? = null) : ReadWriteProperty<Any?, T> = SetOnce(defaultValue)
+
+    private class SetOnce<T>(defaultValue: T? = null) : ReadWriteProperty<Any?, T> {
+        private var isSet = false
+        private var value: T? = defaultValue
+
+        override fun getValue(thisRef: Any?, property: KProperty<*>): T {
+            return value ?: throw IllegalStateException("${property.name} not initialized")
+        }
+
+        override fun setValue(thisRef: Any?, property: KProperty<*>, value: T) = synchronized(this) {
+            if (!isSet) {
+                this.value = value
+                isSet = true
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt
new file mode 100644
index 00000000000..617ac3fe906
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ByteArrayAdapter.kt
@@ -0,0 +1,12 @@
+package org.openapitools.client.infrastructure
+
+import com.squareup.moshi.FromJson
+import com.squareup.moshi.ToJson
+
+class ByteArrayAdapter {
+    @ToJson
+    fun toJson(data: ByteArray): String = String(data)
+
+    @FromJson
+    fun fromJson(data: String): ByteArray = data.toByteArray()
+}
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
new file mode 100644
index 00000000000..2f3b0157ba7
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Errors.kt
@@ -0,0 +1,42 @@
+@file:Suppress("unused")
+package org.openapitools.client.infrastructure
+
+import java.lang.RuntimeException
+
+open class ClientException : RuntimeException {
+
+    /**
+     * Constructs an [ClientException] with no detail message.
+     */
+    constructor() : super()
+
+    /**
+     * Constructs an [ClientException] with the specified detail message.
+
+     * @param   message   the detail message.
+     */
+    constructor(message: kotlin.String) : super(message)
+
+    companion object {
+        private const val serialVersionUID: Long = 123L
+    }
+}
+
+open class ServerException : RuntimeException {
+
+    /**
+     * Constructs an [ServerException] with no detail message.
+     */
+    constructor() : super()
+
+    /**
+     * Constructs an [ServerException] with the specified detail message.
+
+     * @param   message   the detail message.
+     */
+    constructor(message: kotlin.String) : super(message)
+
+    companion object {
+        private const val serialVersionUID: Long = 456L
+    }
+}
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt
new file mode 100644
index 00000000000..b2e1654479a
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateAdapter.kt
@@ -0,0 +1,19 @@
+package org.openapitools.client.infrastructure
+
+import com.squareup.moshi.FromJson
+import com.squareup.moshi.ToJson
+import java.time.LocalDate
+import java.time.format.DateTimeFormatter
+
+class LocalDateAdapter {
+    @ToJson
+    fun toJson(value: LocalDate): String {
+        return DateTimeFormatter.ISO_LOCAL_DATE.format(value)
+    }
+
+    @FromJson
+    fun fromJson(value: String): LocalDate {
+        return LocalDate.parse(value, DateTimeFormatter.ISO_LOCAL_DATE)
+    }
+
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt
new file mode 100644
index 00000000000..e082db94811
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/LocalDateTimeAdapter.kt
@@ -0,0 +1,19 @@
+package org.openapitools.client.infrastructure
+
+import com.squareup.moshi.FromJson
+import com.squareup.moshi.ToJson
+import java.time.LocalDateTime
+import java.time.format.DateTimeFormatter
+
+class LocalDateTimeAdapter {
+    @ToJson
+    fun toJson(value: LocalDateTime): String {
+        return DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(value)
+    }
+
+    @FromJson
+    fun fromJson(value: String): LocalDateTime {
+        return LocalDateTime.parse(value, DateTimeFormatter.ISO_LOCAL_DATE_TIME)
+    }
+
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
new file mode 100644
index 00000000000..53e689237d7
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
@@ -0,0 +1,16 @@
+package org.openapitools.client.infrastructure
+
+/**
+ * Defines a config object for a given request.
+ * NOTE: This object doesn't include 'body' because it
+ *       allows for caching of the constructed object
+ *       for many request definitions.
+ * NOTE: Headers is a Map<String,String> because rfc2616 defines
+ *       multi-valued headers as csv-only.
+ */
+data class RequestConfig(
+    val method: RequestMethod,
+    val path: String,
+    val headers: MutableMap<String, String> = mutableMapOf(),
+    val query: Map<String, List<String>> = mapOf()
+)
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
new file mode 100644
index 00000000000..931b12b8bd7
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
@@ -0,0 +1,8 @@
+package org.openapitools.client.infrastructure
+
+/**
+ * Provides enumerated HTTP verbs
+ */
+enum class RequestMethod {
+    GET, DELETE, HEAD, OPTIONS, PATCH, POST, PUT
+}
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ResponseExtensions.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ResponseExtensions.kt
new file mode 100644
index 00000000000..f50104a6f35
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/ResponseExtensions.kt
@@ -0,0 +1,23 @@
+package org.openapitools.client.infrastructure
+
+import okhttp3.Response
+
+/**
+ * Provides an extension to evaluation whether the response is a 1xx code
+ */
+val Response.isInformational : Boolean get() = this.code() in 100..199
+
+/**
+ * Provides an extension to evaluation whether the response is a 3xx code
+ */
+val Response.isRedirect : Boolean get() = this.code() in 300..399
+
+/**
+ * Provides an extension to evaluation whether the response is a 4xx code
+ */
+val Response.isClientError : Boolean get() = this.code() in 400..499
+
+/**
+ * Provides an extension to evaluation whether the response is a 5xx (Standard) through 999 (non-standard) code
+ */
+val Response.isServerError : Boolean get() = this.code() in 500..999
\ No newline at end of file
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
new file mode 100644
index 00000000000..7c5a353e0f7
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -0,0 +1,18 @@
+package org.openapitools.client.infrastructure
+
+import com.squareup.moshi.Moshi
+import com.squareup.moshi.adapters.Rfc3339DateJsonAdapter
+import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory
+import java.util.Date
+
+object Serializer {
+    @JvmStatic
+    val moshi: Moshi = Moshi.Builder()
+        .add(Date::class.java, Rfc3339DateJsonAdapter().nullSafe())
+        .add(LocalDateTimeAdapter())
+        .add(LocalDateAdapter())
+        .add(UUIDAdapter())
+        .add(ByteArrayAdapter())
+        .add(KotlinJsonAdapterFactory())
+        .build()
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/UUIDAdapter.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/UUIDAdapter.kt
new file mode 100644
index 00000000000..a4a44cc18b7
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/infrastructure/UUIDAdapter.kt
@@ -0,0 +1,13 @@
+package org.openapitools.client.infrastructure
+
+import com.squareup.moshi.FromJson
+import com.squareup.moshi.ToJson
+import java.util.UUID
+
+class UUIDAdapter {
+    @ToJson
+    fun toJson(uuid: UUID) = uuid.toString()
+
+    @FromJson
+    fun fromJson(s: String) = UUID.fromString(s)
+}
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/ApiResponse.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/ApiResponse.kt
new file mode 100644
index 00000000000..4bbbf9bf027
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/ApiResponse.kt
@@ -0,0 +1,35 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.models
+
+
+import com.squareup.moshi.Json
+import android.os.Parcelable
+import kotlinx.android.parcel.Parcelize
+
+/**
+ * Describes the result of uploading an image resource
+ * @param code 
+ * @param type 
+ * @param message 
+ */
+@Parcelize
+
+data class ApiResponse (
+    @Json(name = "code")
+    val code: kotlin.Int? = null,
+    @Json(name = "type")
+    val type: kotlin.String? = null,
+    @Json(name = "message")
+    val message: kotlin.String? = null
+) : Parcelable
+
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Category.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Category.kt
new file mode 100644
index 00000000000..39e411bca0b
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Category.kt
@@ -0,0 +1,32 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.models
+
+
+import com.squareup.moshi.Json
+import android.os.Parcelable
+import kotlinx.android.parcel.Parcelize
+
+/**
+ * A category for a pet
+ * @param id 
+ * @param name 
+ */
+@Parcelize
+
+data class Category (
+    @Json(name = "id")
+    val id: kotlin.Long? = null,
+    @Json(name = "name")
+    val name: kotlin.String? = null
+) : Parcelable
+
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Order.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Order.kt
new file mode 100644
index 00000000000..23d2053b786
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Order.kt
@@ -0,0 +1,64 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.models
+
+
+import com.squareup.moshi.Json
+import android.os.Parcelable
+import kotlinx.android.parcel.Parcelize
+
+/**
+ * An order for a pets from the pet store
+ * @param id 
+ * @param petId 
+ * @param quantity 
+ * @param shipDate 
+ * @param status Order Status
+ * @param complete 
+ */
+@Parcelize
+
+data class Order (
+    @Json(name = "id")
+    val id: kotlin.Long? = null,
+    @Json(name = "petId")
+    val petId: kotlin.Long? = null,
+    @Json(name = "quantity")
+    val quantity: kotlin.Int? = null,
+    @Json(name = "shipDate")
+    val shipDate: java.time.LocalDateTime? = null,
+    /* Order Status */
+    @Json(name = "status")
+    val status: Order.Status? = null,
+    @Json(name = "complete")
+    val complete: kotlin.Boolean? = null
+) : Parcelable
+{
+
+    /**
+    * Order Status
+    * Values: placed,approved,delivered
+    */
+    
+    enum class Status(val value: kotlin.String){
+    
+        @Json(name = "placed") placed("placed"),
+    
+        @Json(name = "approved") approved("approved"),
+    
+        @Json(name = "delivered") delivered("delivered");
+    
+
+    }
+
+}
+
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Pet.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Pet.kt
new file mode 100644
index 00000000000..73c8e903679
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Pet.kt
@@ -0,0 +1,66 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.models
+
+import org.openapitools.client.models.Category
+import org.openapitools.client.models.Tag
+
+import com.squareup.moshi.Json
+import android.os.Parcelable
+import kotlinx.android.parcel.Parcelize
+
+/**
+ * A pet for sale in the pet store
+ * @param id 
+ * @param category 
+ * @param name 
+ * @param photoUrls 
+ * @param tags 
+ * @param status pet status in the store
+ */
+@Parcelize
+
+data class Pet (
+    @Json(name = "name")
+    val name: kotlin.String,
+    @Json(name = "photoUrls")
+    val photoUrls: kotlin.Array<kotlin.String>,
+    @Json(name = "id")
+    val id: kotlin.Long? = null,
+    @Json(name = "category")
+    val category: Category? = null,
+    @Json(name = "tags")
+    val tags: kotlin.Array<Tag>? = null,
+    /* pet status in the store */
+    @Json(name = "status")
+    val status: Pet.Status? = null
+) : Parcelable
+{
+
+    /**
+    * pet status in the store
+    * Values: available,pending,sold
+    */
+    
+    enum class Status(val value: kotlin.String){
+    
+        @Json(name = "available") available("available"),
+    
+        @Json(name = "pending") pending("pending"),
+    
+        @Json(name = "sold") sold("sold");
+    
+
+    }
+
+}
+
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Tag.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Tag.kt
new file mode 100644
index 00000000000..817461e739b
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/Tag.kt
@@ -0,0 +1,32 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.models
+
+
+import com.squareup.moshi.Json
+import android.os.Parcelable
+import kotlinx.android.parcel.Parcelize
+
+/**
+ * A tag for a pet
+ * @param id 
+ * @param name 
+ */
+@Parcelize
+
+data class Tag (
+    @Json(name = "id")
+    val id: kotlin.Long? = null,
+    @Json(name = "name")
+    val name: kotlin.String? = null
+) : Parcelable
+
diff --git a/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/User.kt b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/User.kt
new file mode 100644
index 00000000000..9ed1a2a1188
--- /dev/null
+++ b/samples/client/petstore/kotlin-okhttp3/src/main/kotlin/org/openapitools/client/models/User.kt
@@ -0,0 +1,51 @@
+/**
+* OpenAPI Petstore
+* This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+*
+* 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.models
+
+
+import com.squareup.moshi.Json
+import android.os.Parcelable
+import kotlinx.android.parcel.Parcelize
+
+/**
+ * A User who is purchasing from the pet store
+ * @param id 
+ * @param username 
+ * @param firstName 
+ * @param lastName 
+ * @param email 
+ * @param password 
+ * @param phone 
+ * @param userStatus User Status
+ */
+@Parcelize
+
+data class User (
+    @Json(name = "id")
+    val id: kotlin.Long? = null,
+    @Json(name = "username")
+    val username: kotlin.String? = null,
+    @Json(name = "firstName")
+    val firstName: kotlin.String? = null,
+    @Json(name = "lastName")
+    val lastName: kotlin.String? = null,
+    @Json(name = "email")
+    val email: kotlin.String? = null,
+    @Json(name = "password")
+    val password: kotlin.String? = null,
+    @Json(name = "phone")
+    val phone: kotlin.String? = null,
+    /* User Status */
+    @Json(name = "userStatus")
+    val userStatus: kotlin.Int? = null
+) : Parcelable
+
diff --git a/samples/client/petstore/kotlin-string/build.gradle b/samples/client/petstore/kotlin-string/build.gradle
index c09f7912cfe..98ac4f243e6 100644
--- a/samples/client/petstore/kotlin-string/build.gradle
+++ b/samples/client/petstore/kotlin-string/build.gradle
@@ -32,6 +32,6 @@ dependencies {
     compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
     compile "com.squareup.moshi:moshi-kotlin:1.8.0"
     compile "com.squareup.moshi:moshi-adapters:1.8.0"
-    compile "com.squareup.okhttp3:okhttp:4.0.1"
+    compile "com.squareup.okhttp3:okhttp:4.2.0"
     testImplementation "io.kotlintest:kotlintest-runner-junit5:3.1.0"
 }
diff --git a/samples/client/petstore/kotlin-threetenbp/build.gradle b/samples/client/petstore/kotlin-threetenbp/build.gradle
index b9094d81f32..9cd18f3a5fc 100644
--- a/samples/client/petstore/kotlin-threetenbp/build.gradle
+++ b/samples/client/petstore/kotlin-threetenbp/build.gradle
@@ -32,7 +32,7 @@ dependencies {
     compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
     compile "com.squareup.moshi:moshi-kotlin:1.8.0"
     compile "com.squareup.moshi:moshi-adapters:1.8.0"
-    compile "com.squareup.okhttp3:okhttp:4.0.1"
+    compile "com.squareup.okhttp3:okhttp:4.2.0"
     compile "org.threeten:threetenbp:1.3.8"
     testImplementation "io.kotlintest:kotlintest-runner-junit5:3.1.0"
 }
diff --git a/samples/client/petstore/kotlin/build.gradle b/samples/client/petstore/kotlin/build.gradle
index c09f7912cfe..98ac4f243e6 100644
--- a/samples/client/petstore/kotlin/build.gradle
+++ b/samples/client/petstore/kotlin/build.gradle
@@ -32,6 +32,6 @@ dependencies {
     compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
     compile "com.squareup.moshi:moshi-kotlin:1.8.0"
     compile "com.squareup.moshi:moshi-adapters:1.8.0"
-    compile "com.squareup.okhttp3:okhttp:4.0.1"
+    compile "com.squareup.okhttp3:okhttp:4.2.0"
     testImplementation "io.kotlintest:kotlintest-runner-junit5:3.1.0"
 }