diff --git a/bin/utils/ensure-up-to-date b/bin/utils/ensure-up-to-date
index 11d19b0e8ab..c2e38093de4 100755
--- a/bin/utils/ensure-up-to-date
+++ b/bin/utils/ensure-up-to-date
@@ -52,6 +52,7 @@ declare -a scripts=(
 "./bin/elixir-petstore.sh"
 "./bin/go-petstore.sh"
 "./bin/go-gin-petstore-server.sh"
+"./bin/groovy-petstore.sh"
 #"./bin/elm-petstore-all.sh"
 "./bin/meta-codegen.sh"
 # OTHERS
diff --git a/docs/generators/groovy.md b/docs/generators/groovy.md
index 7719a72dcc9..16d4e284a1e 100644
--- a/docs/generators/groovy.md
+++ b/docs/generators/groovy.md
@@ -42,4 +42,3 @@ sidebar_label: groovy
 |parentArtifactId|parent artifactId in generated pom N.B. parentGroupId, parentArtifactId and parentVersion must all be specified for any of them to take effect| |null|
 |parentVersion|parent version in generated pom N.B. parentGroupId, parentArtifactId and parentVersion must all be specified for any of them to take effect| |null|
 |snapshotVersion|Uses a SNAPSHOT version.|<dl><dt>**true**</dt><dd>Use a SnapShot Version</dd><dt>**false**</dt><dd>Use a Release Version</dd><dl>|null|
-|configPackage|configuration package for generated code| |org.openapitools.configuration|
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java
index 6a1f6460ea9..3c4ec0102c8 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java
@@ -978,10 +978,6 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
         }
     }
 
-    @Override
-    public void postProcessParameter(CodegenParameter parameter) {
-    }
-
     @Override
     public Map<String, Object> postProcessModels(Map<String, Object> objs) {
         // recursively add import for mapping one type to multiple imports
diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GroovyClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GroovyClientCodegen.java
index 90647b83299..94332fed9d8 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GroovyClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/GroovyClientCodegen.java
@@ -17,20 +17,16 @@
 
 package org.openapitools.codegen.languages;
 
-import org.openapitools.codegen.CliOption;
-import org.openapitools.codegen.CodegenConstants;
-import org.openapitools.codegen.CodegenType;
-import org.openapitools.codegen.SupportingFile;
+import org.openapitools.codegen.*;
 
 import java.io.File;
+import java.util.List;
+import java.util.Map;
 
 import static org.openapitools.codegen.utils.StringUtils.camelize;
 
 
 public class GroovyClientCodegen extends AbstractJavaCodegen {
-    public static final String CONFIG_PACKAGE = "configPackage";
-    protected String title = "Petstore Server";
-    protected String configPackage = "org.openapitools.configuration";
 
     public GroovyClientCodegen() {
         super();
@@ -60,18 +56,14 @@ public class GroovyClientCodegen extends AbstractJavaCodegen {
         artifactId = "openapi-groovy";
         dateLibrary = "legacy"; //TODO: add joda support to groovy
 
-        // clioOptions default redifinition need to be updated
+        // clioOptions default redefinition need to be updated
         updateOption(CodegenConstants.SOURCE_FOLDER, this.getSourceFolder());
         updateOption(CodegenConstants.INVOKER_PACKAGE, this.getInvokerPackage());
         updateOption(CodegenConstants.ARTIFACT_ID, this.getArtifactId());
         updateOption(CodegenConstants.API_PACKAGE, apiPackage);
         updateOption(CodegenConstants.MODEL_PACKAGE, modelPackage);
-        updateOption(this.DATE_LIBRARY, this.getDateLibrary());
+        updateOption(DATE_LIBRARY, this.getDateLibrary());
 
-        additionalProperties.put("title", title);
-        additionalProperties.put(CONFIG_PACKAGE, configPackage);
-
-        cliOptions.add(new CliOption(CONFIG_PACKAGE, "configuration package for generated code").defaultValue(this.configPackage));
     }
 
     @Override
@@ -86,25 +78,32 @@ public class GroovyClientCodegen extends AbstractJavaCodegen {
 
     @Override
     public String getHelp() {
-        return "Generates a Groovy API client (beta).";
+        return "Generates a Groovy API client.";
     }
 
     @Override
     public void processOpts() {
         super.processOpts();
 
-        if (additionalProperties.containsKey(CONFIG_PACKAGE)) {
-            this.setConfigPackage((String) additionalProperties.get(CONFIG_PACKAGE));
-        }
-
         supportingFiles.add(new SupportingFile("build.gradle.mustache", "", "build.gradle"));
-        // TODO readme to be added later
-        //supportingFiles.add(new SupportingFile("README.mustache", "", "README.md"));
+        supportingFiles.add(new SupportingFile("README.mustache", "", "README.md"));
         supportingFiles.add(new SupportingFile("ApiUtils.mustache",
                 (sourceFolder + File.separator + apiPackage).replace(".", java.io.File.separator), "ApiUtils.groovy"));
 
     }
 
+    @Override
+    public Map<String, Object> postProcessOperationsWithModels(Map<String, Object> operations, List<Object> allModels) {
+        Map<String, Object> objs = (Map<String, Object>) operations.get("operations");
+
+        List<CodegenOperation> ops = (List<CodegenOperation>) objs.get("operation");
+        for (CodegenOperation op : ops) {
+            // Overwrite path to map variable with path parameters
+            op.path = op.path.replace("{", "${");
+        }
+        return operations;
+    }
+
     @Override
     public String toApiName(String name) {
         if (name.length() == 0) {
@@ -114,10 +113,6 @@ public class GroovyClientCodegen extends AbstractJavaCodegen {
         return camelize(name) + "Api";
     }
 
-    public void setConfigPackage(String configPackage) {
-        this.configPackage = configPackage;
-    }
-
     @Override
     public String escapeQuotationMark(String input) {
         // remove ' to avoid code injection
diff --git a/modules/openapi-generator/src/main/resources/Groovy/ApiUtils.mustache b/modules/openapi-generator/src/main/resources/Groovy/ApiUtils.mustache
index 956b834c88c..95070ee3e73 100644
--- a/modules/openapi-generator/src/main/resources/Groovy/ApiUtils.mustache
+++ b/modules/openapi-generator/src/main/resources/Groovy/ApiUtils.mustache
@@ -1,33 +1,38 @@
-package {{invokerPackage}};
+package {{invokerPackage}}
 
-import groovyx.net.http.HTTPBuilder
-import groovyx.net.http.Method
-
-import static groovyx.net.http.ContentType.JSON
-import static java.net.URI.create;
+import static groovyx.net.http.HttpBuilder.configure
+import static java.net.URI.create
 
 class ApiUtils {
 
-    def invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, method, container, type)  {
+    void invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType, method, container, type)  {
         def (url, uriPath) = buildUrlAndUriPath(basePath, versionPath, resourcePath)
         println "url=$url uriPath=$uriPath"
-        def http = new HTTPBuilder(url)
-        http.request( Method.valueOf(method), JSON ) {
-            uri.path = uriPath
-            uri.query = queryParams
-            response.success = { resp, json ->
+        def http = configure {
+            request.uri = url
+            request.uri.path = uriPath
+        }
+        .invokeMethod(String.valueOf(method).toLowerCase()) {
+            request.uri.query = queryParams
+            request.headers = headerParams
+            if (bodyParams != null) {
+                request.body = bodyParams
+            }
+            request.contentType = contentType
+
+            response.success { resp, json ->
                 if (type != null) {
                     onSuccess(parse(json, container, type))
                 }
             }
-            response.failure = { resp ->
-                onFailure(resp.status, resp.statusLine.reasonPhrase)
+            response.failure { resp ->
+                onFailure(resp.statusCode, resp.message)
             }
         }
+
     }
 
-
-    def buildUrlAndUriPath(basePath, versionPath, resourcePath) {
+    private static def buildUrlAndUriPath(basePath, versionPath, resourcePath) {
         // HTTPBuilder expects to get as its constructor parameter an URL,
         // without any other additions like path, therefore we need to cut the path
         // from the basePath as it is represented by swagger APIs
@@ -38,12 +43,11 @@ class ApiUtils {
         [basePath-pathOnly, pathOnly+versionPath+resourcePath]
     }
 
-
-    def parse(object, container, clazz) {
-        if (container == "List") {
+    private def parse(object, container, clazz) {
+        if (container == "array") {
             return object.collect {parse(it, "", clazz)}
         }   else {
-                return clazz.newInstance(object)
+            return clazz.newInstance(object)
         }
     }
 
diff --git a/modules/openapi-generator/src/main/resources/Groovy/README.mustache b/modules/openapi-generator/src/main/resources/Groovy/README.mustache
new file mode 100644
index 00000000000..110389077c5
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/Groovy/README.mustache
@@ -0,0 +1,62 @@
+# {{packageName}}
+
+{{#appDescription}}
+{{{appDescription}}}
+{{/appDescription}}
+
+This Groovy package, using the [http-builder-ng library](https://http-builder-ng.github.io/http-builder-ng/), is automatically generated by the [OpenAPI Generator](https://openapi-generator.tech) project:
+
+- API version: {{appVersion}}
+{{#artifactVersion}}
+- Package version: {{artifactVersion}}
+{{/artifactVersion}}
+{{^hideGenerationTimestamp}}
+- Build date: {{generatedDate}}
+{{/hideGenerationTimestamp}}
+- Build package: {{generatorClass}}
+{{#infoUrl}}
+For more information, please visit [{{{infoUrl}}}]({{{infoUrl}}})
+{{/infoUrl}}
+
+## Requirements
+
+* Groovy 2.5.9
+* Gradle 4.9
+
+## Build
+
+First, create the gradle wrapper script:
+
+```
+gradle wrapper
+```
+
+Then, run:
+
+```
+./gradlew check assemble
+```
+
+## Getting Started
+
+{{#apiInfo}}{{#apis}}{{#-first}}{{#operations}}{{#operation}}{{#-first}}
+```groovy
+def apiInstance = new {{classname}}()
+{{#allParams}}def {{paramName}} = {{{example}}} // {{{dataType}}} | {{{description}}}
+{{/allParams}}
+
+apiInstance.{{{operationId}}}({{#allParams}}{{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}})
+    {
+    // on success
+    {{#returnType}}def result = ({{returnType}})it
+    println result
+    {{/returnType}}
+    {{^returnType}}println it{{/returnType}}
+}
+    {
+    // on failure
+    statusCode, message ->
+        println "${statusCode} ${message}"
+};
+```
+{{/-first}}{{/operation}}{{/operations}}{{/-first}}{{/apis}}{{/apiInfo}}
diff --git a/modules/openapi-generator/src/main/resources/Groovy/api.mustache b/modules/openapi-generator/src/main/resources/Groovy/api.mustache
index d20f050432a..20fe23f9623 100644
--- a/modules/openapi-generator/src/main/resources/Groovy/api.mustache
+++ b/modules/openapi-generator/src/main/resources/Groovy/api.mustache
@@ -1,51 +1,86 @@
 package {{package}};
 
-import groovyx.net.http.*
-import static groovyx.net.http.ContentType.*
-import static groovyx.net.http.Method.*
 import {{invokerPackage}}.ApiUtils
-
 {{#imports}}import {{import}}
 {{/imports}}
 
-import java.util.*;
-
-@Mixin(ApiUtils)
 {{#operations}}
 class {{classname}} {
     String basePath = "{{{basePath}}}"
-    String versionPath = "/api/v1"
+    String versionPath = ""
+    ApiUtils apiUtils = new ApiUtils();
 
     {{#operation}}
     def {{operationId}} ({{#allParams}} {{{dataType}}} {{paramName}},{{/allParams}} Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "{{{path}}}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
-        {{#allParams}}
-        {{#required}}
+        {{#allParams}}{{#required}}
         // verify required params are set
         if ({{paramName}} == null) {
             throw new RuntimeException("missing required params {{paramName}}")
         }
+        {{/required}}{{/allParams}}
 
-        {{/required}}
-        {{/allParams}}
         {{#queryParams}}
-        if (!"null".equals(String.valueOf({{paramName}})))
-            queryParams.put("{{baseName}}", String.valueOf({{paramName}}))
-
+        if ({{paramName}} != null) {
+            queryParams.put("{{baseName}}", {{paramName}})
+        }
         {{/queryParams}}
+
         {{#headerParams}}
-        headerParams.put("{{baseName}}", {{paramName}})
-
+        if ({{paramName}} != null) {
+            headerParams.put("{{baseName}}", {{paramName}})
+        }
         {{/headerParams}}
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+        {{#bodyParam}}
+        {{^consumes}}
+        contentType = 'application/json';
+        {{/consumes}}
+        {{#consumes.0}}
+        contentType = '{{{mediaType}}}';
+        {{/consumes.0}}
+        {{/bodyParam}}
+        {{#bodyParams}}
+        // only one body parameter
+        if (1 == {{bodyParams.size}}) {
+            bodyParams = {{paramName}}
+        }
+        // array of body parameters
+        else {
+            bodyParams.put("{{baseName}}", {{paramName}})
+        }
+        {{/bodyParams}}
+
+        {{#hasFormParams}}
+        {{#consumes.0}}
+        contentType = '{{{mediaType}}}';
+        {{/consumes.0}}
+        {{#formParams.0}}
+        // only one form parameter
+        if (1 == {{formParams.size}}) {
+            bodyParams = {{paramName}}
+        }
+        // array of form parameters
+        else {
+            bodyParams = [:]
+        }
+        {{/formParams.0}}
+        {{#formParams}}
+        // array of form parameters
+        if (1 < {{formParams.size}}) {
+            bodyParams.put("{{baseName}}", {{paramName}})
+        }
+        {{/formParams}}
+        {{/hasFormParams}}
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "{{httpMethod}}", "{{returnContainer}}",
                     {{#returnBaseType}}{{{returnBaseType}}}.class {{/returnBaseType}}{{^returnBaseType}}null {{/returnBaseType}})
 
diff --git a/modules/openapi-generator/src/main/resources/Groovy/build.gradle.mustache b/modules/openapi-generator/src/main/resources/Groovy/build.gradle.mustache
index ee7f2e16a7b..b7423c1ef35 100644
--- a/modules/openapi-generator/src/main/resources/Groovy/build.gradle.mustache
+++ b/modules/openapi-generator/src/main/resources/Groovy/build.gradle.mustache
@@ -6,6 +6,11 @@ group = '{{groupId}}'
 version = '{{artifactVersion}}'
 archivesBaseName = 'openapi-gen-groovy'
 
+wrapper {
+    gradleVersion = '4.9'
+    distributionUrl = "https://services.gradle.org/distributions/gradle-$gradleVersion-all.zip"
+}
+
 buildscript {
     repositories {
         maven { url 'https://repo.jfrog.org/artifactory/gradle-plugins' }
@@ -22,19 +27,17 @@ repositories {
 
 ext {
     swagger_annotations_version = "1.5.22"
-    jackson_version = "2.8.11"
-    jackson_databind_version = "2.8.11.3"
+    jackson_version = "2.9.8"
 }
 
 dependencies {
-    compile 'org.codehaus.groovy:groovy-all:2.4.6'
+    compile 'org.codehaus.groovy:groovy-all:2.5.6'
     compile "io.swagger:swagger-annotations:$swagger_annotations_version"
     compile "com.fasterxml.jackson.core:jackson-core:$jackson_version"
     compile "com.fasterxml.jackson.core:jackson-annotations:$jackson_version"
-    compile "com.fasterxml.jackson.core:jackson-databind:$jackson_databind_version"
+    compile "com.fasterxml.jackson.core:jackson-databind:$jackson_version"
     compile "com.fasterxml.jackson.jaxrs:jackson-jaxrs-json-provider:$jackson_version"
-    compile "com.fasterxml.jackson.datatype:jackson-datatype-joda:2.1.5"
-    compile 'org.codehaus.groovy.modules.http-builder:http-builder:0.7.1'
+    compile "com.fasterxml.jackson.datatype:jackson-datatype-joda:$jackson_version"
+    compile 'io.github.http-builder-ng:http-builder-ng-core:1.0.3'
+    testCompile "junit:junit:4.11"
 }
-
-task wrapper(type: Wrapper) { gradleVersion = '1.6' }
diff --git a/modules/openapi-generator/src/main/resources/Groovy/model.mustache b/modules/openapi-generator/src/main/resources/Groovy/model.mustache
index 07c0405c98c..e1821824d79 100644
--- a/modules/openapi-generator/src/main/resources/Groovy/model.mustache
+++ b/modules/openapi-generator/src/main/resources/Groovy/model.mustache
@@ -10,11 +10,8 @@ import {{import}};
 @Canonical
 class {{classname}} {
     {{#vars}}
-    {{#description}}
-    /* {{{description}}} */
-    {{/description}}
+    {{#description}}/* {{{description}}} */{{/description}}
     {{{dataType}}} {{name}}{{#defaultValue}} = {{{defaultValue}}}{{/defaultValue}}
-
     {{/vars}}
 }
 {{/model}}
diff --git a/pom.xml b/pom.xml
index ab648268ec2..46522a7a7a2 100644
--- a/pom.xml
+++ b/pom.xml
@@ -1019,7 +1019,6 @@
                 <module>samples/client/petstore/dart-jaguar/flutter_petstore/openapi</module>-->
                 <!--<module>samples/client/petstore/dart2/petstore</module>-->
                 <module>samples/client/petstore/elm-0.18</module>
-                <module>samples/client/petstore/groovy</module>
                 <module>samples/client/petstore/rust</module>
                 <module>samples/client/petstore/rust-reqwest</module>
                 <!--<module>samples/client/petstore/perl</module>-->
@@ -1096,6 +1095,7 @@
                 <module>samples/client/petstore/java/resteasy</module>
                 <module>samples/client/petstore/java/google-api-client</module>
                 <module>samples/client/petstore/java/rest-assured</module>
+                <module>samples/client/petstore/groovy</module>
                 <!-- servers -->
                 <module>samples/server/petstore/jaxrs-jersey</module>
                 <module>samples/server/petstore/jaxrs-spec</module>
@@ -1176,7 +1176,6 @@
                 <module>samples/client/petstore/java/vertx</module>
                 <module>samples/client/petstore/java/resteasy</module>
                 <module>samples/client/petstore/java/google-api-client</module>
-                <!-- <module>samples/client/petstore/kotlin/</module> -->
                 <!-- servers -->
                 <module>samples/server/petstore/jaxrs-jersey</module>
                 <module>samples/server/petstore/jaxrs-spec</module>
@@ -1222,6 +1221,9 @@
                 <module>samples/client/petstore/elixir</module>
                 <module>samples/client/petstore/erlang-client</module>
                 <module>samples/client/petstore/erlang-proper</module>
+                <module>samples/client/petstore/kotlin/</module>
+                <module>samples/client/petstore/kotlin-threetenbp/</module>
+                <module>samples/client/petstore/kotlin-string/</module>
                 <!-- servers -->
                 <module>samples/server/petstore/erlang-server</module>
                 <module>samples/server/petstore/jaxrs/jersey2</module>
@@ -1229,9 +1231,6 @@
                 <module>samples/server/petstore/spring-mvc</module>
                 <module>samples/server/petstore/spring-mvc-j8-async</module>
                 <module>samples/server/petstore/spring-mvc-j8-localdatetime</module>
-                <module>samples/client/petstore/kotlin/</module>
-                <module>samples/client/petstore/kotlin-threetenbp/</module>
-                <module>samples/client/petstore/kotlin-string/</module>
             </modules>
         </profile>
         <!-- test with Haskell -->
diff --git a/samples/client/petstore/groovy/README.md b/samples/client/petstore/groovy/README.md
new file mode 100644
index 00000000000..9a975239181
--- /dev/null
+++ b/samples/client/petstore/groovy/README.md
@@ -0,0 +1,48 @@
+# 
+
+This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+
+This Groovy package, using the [http-builder-ng library](https://http-builder-ng.github.io/http-builder-ng/), is automatically generated by the [OpenAPI Generator](https://openapi-generator.tech) project:
+
+- API version: 1.0.0
+- Package version: 1.0.0
+- Build package: org.openapitools.codegen.languages.GroovyClientCodegen
+
+## Requirements
+
+* Groovy 2.5.9
+* Gradle 4.9
+
+## Build
+
+First, create the gradle wrapper script:
+
+```
+gradle wrapper
+```
+
+Then, run:
+
+```
+./gradlew check assemble
+```
+
+## Getting Started
+
+
+```groovy
+def apiInstance = new PetApi()
+def body = new Pet() // Pet | Pet object that needs to be added to the store
+
+apiInstance.addPet(body)
+    {
+    // on success
+        println it
+}
+    {
+    // on failure
+    statusCode, message ->
+        println "${statusCode} ${message}"
+};
+```
+
diff --git a/samples/client/petstore/groovy/build.gradle b/samples/client/petstore/groovy/build.gradle
index 30b440b4dd4..ce8d213336a 100644
--- a/samples/client/petstore/groovy/build.gradle
+++ b/samples/client/petstore/groovy/build.gradle
@@ -6,6 +6,11 @@ group = 'org.openapitools'
 version = '1.0.0'
 archivesBaseName = 'openapi-gen-groovy'
 
+wrapper {
+    gradleVersion = '4.9'
+    distributionUrl = "https://services.gradle.org/distributions/gradle-$gradleVersion-all.zip"
+}
+
 buildscript {
     repositories {
         maven { url 'https://repo.jfrog.org/artifactory/gradle-plugins' }
@@ -22,19 +27,17 @@ repositories {
 
 ext {
     swagger_annotations_version = "1.5.22"
-    jackson_version = "2.8.11"
-    jackson_databind_version = "2.8.11.3"
+    jackson_version = "2.9.8"
 }
 
 dependencies {
-    compile 'org.codehaus.groovy:groovy-all:2.4.6'
+    compile 'org.codehaus.groovy:groovy-all:2.5.6'
     compile "io.swagger:swagger-annotations:$swagger_annotations_version"
     compile "com.fasterxml.jackson.core:jackson-core:$jackson_version"
     compile "com.fasterxml.jackson.core:jackson-annotations:$jackson_version"
-    compile "com.fasterxml.jackson.core:jackson-databind:$jackson_databind_version"
+    compile "com.fasterxml.jackson.core:jackson-databind:$jackson_version"
     compile "com.fasterxml.jackson.jaxrs:jackson-jaxrs-json-provider:$jackson_version"
-    compile "com.fasterxml.jackson.datatype:jackson-datatype-joda:2.1.5"
-    compile 'org.codehaus.groovy.modules.http-builder:http-builder:0.7.1'
+    compile "com.fasterxml.jackson.datatype:jackson-datatype-joda:$jackson_version"
+    compile 'io.github.http-builder-ng:http-builder-ng-core:1.0.3'
+    testCompile "junit:junit:4.11"
 }
-
-task wrapper(type: Wrapper) { gradleVersion = '1.6' }
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/ApiUtils.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/ApiUtils.groovy
index 0e3473e879f..c1fe94b1027 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/ApiUtils.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/ApiUtils.groovy
@@ -1,33 +1,38 @@
-package org.openapitools.api;
+package org.openapitools.api
 
-import groovyx.net.http.HTTPBuilder
-import groovyx.net.http.Method
-
-import static groovyx.net.http.ContentType.JSON
-import static java.net.URI.create;
+import static groovyx.net.http.HttpBuilder.configure
+import static java.net.URI.create
 
 class ApiUtils {
 
-    def invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, method, container, type)  {
+    void invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType, method, container, type)  {
         def (url, uriPath) = buildUrlAndUriPath(basePath, versionPath, resourcePath)
         println "url=$url uriPath=$uriPath"
-        def http = new HTTPBuilder(url)
-        http.request( Method.valueOf(method), JSON ) {
-            uri.path = uriPath
-            uri.query = queryParams
-            response.success = { resp, json ->
+        def http = configure {
+            request.uri = url
+            request.uri.path = uriPath
+        }
+        .invokeMethod(String.valueOf(method).toLowerCase()) {
+            request.uri.query = queryParams
+            request.headers = headerParams
+            if (bodyParams != null) {
+                request.body = bodyParams
+            }
+            request.contentType = contentType
+
+            response.success { resp, json ->
                 if (type != null) {
                     onSuccess(parse(json, container, type))
                 }
             }
-            response.failure = { resp ->
-                onFailure(resp.status, resp.statusLine.reasonPhrase)
+            response.failure { resp ->
+                onFailure(resp.statusCode, resp.message)
             }
         }
+
     }
 
-
-    def buildUrlAndUriPath(basePath, versionPath, resourcePath) {
+    private static def buildUrlAndUriPath(basePath, versionPath, resourcePath) {
         // HTTPBuilder expects to get as its constructor parameter an URL,
         // without any other additions like path, therefore we need to cut the path
         // from the basePath as it is represented by swagger APIs
@@ -38,12 +43,11 @@ class ApiUtils {
         [basePath-pathOnly, pathOnly+versionPath+resourcePath]
     }
 
-
-    def parse(object, container, clazz) {
-        if (container == "List") {
+    private def parse(object, container, clazz) {
+        if (container == "array") {
             return object.collect {parse(it, "", clazz)}
         }   else {
-                return clazz.newInstance(object)
+            return clazz.newInstance(object)
         }
     }
 
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/PetApi.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/PetApi.groovy
index 4dd50a1b29f..c022982020a 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/PetApi.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/PetApi.groovy
@@ -1,191 +1,278 @@
 package org.openapitools.api;
 
-import groovyx.net.http.*
-import static groovyx.net.http.ContentType.*
-import static groovyx.net.http.Method.*
 import org.openapitools.api.ApiUtils
-
 import org.openapitools.model.ModelApiResponse
 import org.openapitools.model.Pet
 
-import java.util.*;
-
-@Mixin(ApiUtils)
 class PetApi {
     String basePath = "http://petstore.swagger.io/v2"
-    String versionPath = "/api/v1"
+    String versionPath = ""
+    ApiUtils apiUtils = new ApiUtils();
 
     def addPet ( Pet body, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/pet"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (body == null) {
             throw new RuntimeException("missing required params body")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+        contentType = 'application/json';
+        // only one body parameter
+        if (1 == 1) {
+            bodyParams = body
+        }
+        // array of body parameters
+        else {
+            bodyParams.put("body", body)
+        }
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "POST", "",
                     null )
 
     }
 
     def deletePet ( Long petId, String apiKey, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/pet/{petId}"
+        String resourcePath = "/pet/${petId}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (petId == null) {
             throw new RuntimeException("missing required params petId")
         }
+        
 
-        headerParams.put("api_key", apiKey)
 
-        // TODO: form params, body param not yet support
+        if (apiKey != null) {
+            headerParams.put("api_key", apiKey)
+        }
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "DELETE", "",
                     null )
 
     }
 
     def findPetsByStatus ( List<String> status, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/pet/findByStatus"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (status == null) {
             throw new RuntimeException("missing required params status")
         }
+        
 
-        if (!"null".equals(String.valueOf(status)))
-            queryParams.put("status", String.valueOf(status))
+        if (status != null) {
+            queryParams.put("status", status)
+        }
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "GET", "array",
                     Pet.class )
 
     }
 
     def findPetsByTags ( List<String> tags, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/pet/findByTags"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (tags == null) {
             throw new RuntimeException("missing required params tags")
         }
+        
 
-        if (!"null".equals(String.valueOf(tags)))
-            queryParams.put("tags", String.valueOf(tags))
+        if (tags != null) {
+            queryParams.put("tags", tags)
+        }
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "GET", "array",
                     Pet.class )
 
     }
 
     def getPetById ( Long petId, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/pet/{petId}"
+        String resourcePath = "/pet/${petId}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (petId == null) {
             throw new RuntimeException("missing required params petId")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "GET", "",
                     Pet.class )
 
     }
 
     def updatePet ( Pet body, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/pet"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (body == null) {
             throw new RuntimeException("missing required params body")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+        contentType = 'application/json';
+        // only one body parameter
+        if (1 == 1) {
+            bodyParams = body
+        }
+        // array of body parameters
+        else {
+            bodyParams.put("body", body)
+        }
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "PUT", "",
                     null )
 
     }
 
     def updatePetWithForm ( Long petId, String name, String status, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/pet/{petId}"
+        String resourcePath = "/pet/${petId}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (petId == null) {
             throw new RuntimeException("missing required params petId")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+        contentType = 'application/x-www-form-urlencoded';
+        // only one form parameter
+        if (1 == 2) {
+            bodyParams = name
+        }
+        // array of form parameters
+        else {
+            bodyParams = [:]
+        }
+        // array of form parameters
+        if (1 < 2) {
+            bodyParams.put("name", name)
+        }
+        // array of form parameters
+        if (1 < 2) {
+            bodyParams.put("status", status)
+        }
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "POST", "",
                     null )
 
     }
 
     def uploadFile ( Long petId, String additionalMetadata, File file, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/pet/{petId}/uploadImage"
+        String resourcePath = "/pet/${petId}/uploadImage"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (petId == null) {
             throw new RuntimeException("missing required params petId")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+        contentType = 'multipart/form-data';
+        // only one form parameter
+        if (1 == 2) {
+            bodyParams = additionalMetadata
+        }
+        // array of form parameters
+        else {
+            bodyParams = [:]
+        }
+        // array of form parameters
+        if (1 < 2) {
+            bodyParams.put("additionalMetadata", additionalMetadata)
+        }
+        // array of form parameters
+        if (1 < 2) {
+            bodyParams.put("file", file)
+        }
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "POST", "",
                     ModelApiResponse.class )
 
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/StoreApi.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/StoreApi.groovy
index 0650a7232b1..154551d1880 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/StoreApi.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/StoreApi.groovy
@@ -1,93 +1,116 @@
 package org.openapitools.api;
 
-import groovyx.net.http.*
-import static groovyx.net.http.ContentType.*
-import static groovyx.net.http.Method.*
 import org.openapitools.api.ApiUtils
-
 import org.openapitools.model.Order
 
-import java.util.*;
-
-@Mixin(ApiUtils)
 class StoreApi {
     String basePath = "http://petstore.swagger.io/v2"
-    String versionPath = "/api/v1"
+    String versionPath = ""
+    ApiUtils apiUtils = new ApiUtils();
 
     def deleteOrder ( String orderId, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/store/order/{orderId}"
+        String resourcePath = "/store/order/${orderId}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (orderId == null) {
             throw new RuntimeException("missing required params orderId")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "DELETE", "",
                     null )
 
     }
 
     def getInventory ( Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/store/inventory"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
-        // TODO: form params, body param not yet support
+        
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "GET", "map",
                     Integer.class )
 
     }
 
     def getOrderById ( Long orderId, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/store/order/{orderId}"
+        String resourcePath = "/store/order/${orderId}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (orderId == null) {
             throw new RuntimeException("missing required params orderId")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "GET", "",
                     Order.class )
 
     }
 
     def placeOrder ( Order body, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/store/order"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (body == null) {
             throw new RuntimeException("missing required params body")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+        contentType = 'application/json';
+        // only one body parameter
+        if (1 == 1) {
+            bodyParams = body
+        }
+        // array of body parameters
+        else {
+            bodyParams.put("body", body)
+        }
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "POST", "",
                     Order.class )
 
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/UserApi.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/UserApi.groovy
index 0c768494640..2d0ec2ab73c 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/UserApi.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/api/UserApi.groovy
@@ -1,193 +1,264 @@
 package org.openapitools.api;
 
-import groovyx.net.http.*
-import static groovyx.net.http.ContentType.*
-import static groovyx.net.http.Method.*
 import org.openapitools.api.ApiUtils
-
+import java.util.List
 import org.openapitools.model.User
 
-import java.util.*;
-
-@Mixin(ApiUtils)
 class UserApi {
     String basePath = "http://petstore.swagger.io/v2"
-    String versionPath = "/api/v1"
+    String versionPath = ""
+    ApiUtils apiUtils = new ApiUtils();
 
     def createUser ( User body, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/user"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (body == null) {
             throw new RuntimeException("missing required params body")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+        contentType = 'application/json';
+        // only one body parameter
+        if (1 == 1) {
+            bodyParams = body
+        }
+        // array of body parameters
+        else {
+            bodyParams.put("body", body)
+        }
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "POST", "",
                     null )
 
     }
 
     def createUsersWithArrayInput ( List<User> body, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/user/createWithArray"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (body == null) {
             throw new RuntimeException("missing required params body")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+        contentType = 'application/json';
+        // only one body parameter
+        if (1 == 1) {
+            bodyParams = body
+        }
+        // array of body parameters
+        else {
+            bodyParams.put("body", body)
+        }
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "POST", "",
                     null )
 
     }
 
     def createUsersWithListInput ( List<User> body, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/user/createWithList"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (body == null) {
             throw new RuntimeException("missing required params body")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+        contentType = 'application/json';
+        // only one body parameter
+        if (1 == 1) {
+            bodyParams = body
+        }
+        // array of body parameters
+        else {
+            bodyParams.put("body", body)
+        }
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "POST", "",
                     null )
 
     }
 
     def deleteUser ( String username, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/user/{username}"
+        String resourcePath = "/user/${username}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (username == null) {
             throw new RuntimeException("missing required params username")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "DELETE", "",
                     null )
 
     }
 
     def getUserByName ( String username, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/user/{username}"
+        String resourcePath = "/user/${username}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (username == null) {
             throw new RuntimeException("missing required params username")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "GET", "",
                     User.class )
 
     }
 
     def loginUser ( String username, String password, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/user/login"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (username == null) {
             throw new RuntimeException("missing required params username")
         }
-
+        
         // verify required params are set
         if (password == null) {
             throw new RuntimeException("missing required params password")
         }
+        
 
-        if (!"null".equals(String.valueOf(username)))
-            queryParams.put("username", String.valueOf(username))
+        if (username != null) {
+            queryParams.put("username", username)
+        }
+        if (password != null) {
+            queryParams.put("password", password)
+        }
 
-        if (!"null".equals(String.valueOf(password)))
-            queryParams.put("password", String.valueOf(password))
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "GET", "",
                     String.class )
 
     }
 
     def logoutUser ( Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
         String resourcePath = "/user/logout"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
-        // TODO: form params, body param not yet support
+        
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "GET", "",
                     null )
 
     }
 
     def updateUser ( String username, User body, Closure onSuccess, Closure onFailure)  {
-        // create path and map path parameters (TODO)
-        String resourcePath = "/user/{username}"
+        String resourcePath = "/user/${username}"
 
-        // query params
+        // params
         def queryParams = [:]
         def headerParams = [:]
+        def bodyParams
+        def contentType
 
+        
         // verify required params are set
         if (username == null) {
             throw new RuntimeException("missing required params username")
         }
-
+        
         // verify required params are set
         if (body == null) {
             throw new RuntimeException("missing required params body")
         }
+        
 
-        // TODO: form params, body param not yet support
 
-        invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams,
+
+        contentType = 'application/json';
+        // only one body parameter
+        if (1 == 1) {
+            bodyParams = body
+        }
+        // array of body parameters
+        else {
+            bodyParams.put("body", body)
+        }
+
+
+        apiUtils.invokeApi(onSuccess, onFailure, basePath, versionPath, resourcePath, queryParams, headerParams, bodyParams, contentType,
                     "PUT", "",
                     null )
 
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Category.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Category.groovy
index 305a861bd28..d8ccf48a82a 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Category.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Category.groovy
@@ -6,8 +6,8 @@ import io.swagger.annotations.ApiModelProperty;
 
 @Canonical
 class Category {
+    
     Long id
-
+    
     String name
-
 }
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/ModelApiResponse.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/ModelApiResponse.groovy
index 9a1f4fe1680..468841ffff3 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/ModelApiResponse.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/ModelApiResponse.groovy
@@ -6,10 +6,10 @@ import io.swagger.annotations.ApiModelProperty;
 
 @Canonical
 class ModelApiResponse {
+    
     Integer code
-
+    
     String type
-
+    
     String message
-
 }
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Order.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Order.groovy
index 6bbffdbd7c9..d9e02f8a6cc 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Order.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Order.groovy
@@ -6,17 +6,16 @@ import io.swagger.annotations.ApiModelProperty;
 
 @Canonical
 class Order {
+    
     Long id
-
+    
     Long petId
-
+    
     Integer quantity
-
+    
     Date shipDate
-
     /* Order Status */
     String status
-
+    
     Boolean complete = false
-
 }
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Pet.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Pet.groovy
index eb62fc15ff3..ab4b87def72 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Pet.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Pet.groovy
@@ -10,17 +10,16 @@ import org.openapitools.model.Tag;
 
 @Canonical
 class Pet {
+    
     Long id
-
+    
     Category category = null
-
+    
     String name
-
+    
     List<String> photoUrls = new ArrayList<String>()
-
+    
     List<Tag> tags = new ArrayList<Tag>()
-
     /* pet status in the store */
     String status
-
 }
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Tag.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Tag.groovy
index 64f08ade6a4..a704bc5ffef 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Tag.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/Tag.groovy
@@ -6,8 +6,8 @@ import io.swagger.annotations.ApiModelProperty;
 
 @Canonical
 class Tag {
+    
     Long id
-
+    
     String name
-
 }
diff --git a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/User.groovy b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/User.groovy
index ed6ebe83392..a6f850e8754 100644
--- a/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/User.groovy
+++ b/samples/client/petstore/groovy/src/main/groovy/org/openapitools/model/User.groovy
@@ -6,21 +6,20 @@ import io.swagger.annotations.ApiModelProperty;
 
 @Canonical
 class User {
+    
     Long id
-
+    
     String username
-
+    
     String firstName
-
+    
     String lastName
-
+    
     String email
-
+    
     String password
-
+    
     String phone
-
     /* User Status */
     Integer userStatus
-
 }
diff --git a/samples/client/petstore/groovy/src/test/groovy/openapitools/PetApiTest.groovy b/samples/client/petstore/groovy/src/test/groovy/openapitools/PetApiTest.groovy
new file mode 100644
index 00000000000..d62103e4cab
--- /dev/null
+++ b/samples/client/petstore/groovy/src/test/groovy/openapitools/PetApiTest.groovy
@@ -0,0 +1,119 @@
+package openapitools
+
+import org.junit.Test
+import org.openapitools.api.PetApi
+import org.openapitools.model.Category
+import org.openapitools.model.Pet
+import org.openapitools.model.Tag
+
+
+class PetApiTest extends GroovyTestCase  {
+
+    Long petId = 10009;
+    PetApi petApi = new PetApi()
+
+    @Test
+    void testAddAndGetPet() {
+        def pet = new Pet()
+        pet.setId(this.petId)
+        pet.setName("groovy client test")
+        pet.setPhotoUrls(["http://test_groovy_unit_test.com"])
+        pet.setCategory(new Category(this.petId, "test groovy category"))
+        pet.setTags([new Tag(this.petId, "test groovy tag")])
+        this.petApi.addPet(pet) {
+        }
+        {
+            statusCode, message ->
+                assertEquals(200, statusCode)
+        };
+
+        this.petApi.getPetById(this.petId) {
+            def petGetted = (Pet)it
+            assertEquals(this.petId, petGetted.getId())
+            assertEquals("groovy client test", petGetted.getName())
+            assertEquals(this.petId, petGetted.getCategory().getId())
+            assertEquals("test groovy category", petGetted.getCategory().getName())
+            assertEquals(this.petId, petGetted.getTags()[0].id)
+            assertEquals("test groovy tag", petGetted.getTags()[0].name)
+        }
+        {
+            statusCode, message ->
+                assertEquals(200, statusCode)
+        };
+
+    }
+
+    @Test
+    void testUpdateOnePet() {
+        def pet = new Pet()
+        pet.setId(this.petId)
+        pet.setName("groovy client updatetest")
+        pet.setStatus("pending")
+        this.petApi.updatePet(pet) {
+        }
+        {
+            statusCode, message ->
+                assertEquals(200, statusCode)
+        };
+
+        this.petApi.getPetById(this.petId) {
+            def petGetted = (Pet)it
+            assertEquals(this.petId, petGetted.getId())
+            assertEquals("groovy client updatetest", petGetted.getName())
+            assertEquals("pending", petGetted.getStatus())
+        }
+        {
+            statusCode, message ->
+                assertEquals(200, statusCode)
+        };
+
+        this.petApi.updatePetWithForm(this.petId, "groovy client updatetestwithform", "sold") {
+        }
+                {
+                    statusCode, message ->
+                        assertEquals(200, statusCode)
+                };
+
+        this.petApi.getPetById(this.petId) {
+            def petGetted = (Pet)it
+            assertEquals(this.petId, petGetted.getId())
+            assertEquals("groovy client updatetestwithform", petGetted.getName())
+            assertEquals("sold", petGetted.getStatus())
+        }
+                {
+                    statusCode, message ->
+                        assertEquals(200, statusCode)
+                };
+
+        this.petApi.deletePet(this.petId, "apiKey") {
+        }
+{
+            statusCode, message ->
+                assertEquals(200, statusCode)
+        };
+
+        // should throw a 404 after delete
+        this.petApi.getPetById(this.petId) {
+            assertEquals(404, 200)
+        }
+{
+            statusCode, message ->
+                assertEquals(404, statusCode)
+        };
+
+    }
+
+    @Test
+    void testGetPetByStatus() {
+        this.petApi.findPetsByStatus(["sold"]) {
+            def listPets = (ArrayList)it
+            assertTrue(listPets.size() > 0)
+        }
+        {
+            statusCode, message ->
+                assertEquals(200, statusCode)
+        };
+
+    }
+
+}