use map/array model class only if it is generated (#17612)

* fix

* tests

* generate samples

* refactor

samples/client/petstore/java/resttemplate-withXml/docs/FakeApi.md

@@ -25,6 +25,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | [**testJsonFormData**](FakeApi.md#testJsonFormData) | **GET** /fake/jsonFormData | test json serialization of form data |
 | [**testNullable**](FakeApi.md#testNullable) | **POST** /fake/nullable | test nullable parent property |
 | [**testQueryParameterCollectionFormat**](FakeApi.md#testQueryParameterCollectionFormat) | **PUT** /fake/test-query-parameters |  |
+| [**testStringMapReference**](FakeApi.md#testStringMapReference) | **POST** /fake/stringMap-reference | test referenced string map |
 
 
 
@@ -1473,3 +1474,68 @@ No authorization required
 |-------------|-------------|------------------|
 | **200** | Success |  -  |
 
+
+## testStringMapReference
+
+> testStringMapReference(requestBody)
+
+test referenced string map
+
+
+
+### Example
+
+```java
+// Import classes:
+import org.openapitools.client.ApiClient;
+import org.openapitools.client.ApiException;
+import org.openapitools.client.Configuration;
+import org.openapitools.client.models.*;
+import org.openapitools.client.api.FakeApi;
+
+public class Example {
+    public static void main(String[] args) {
+        ApiClient defaultClient = Configuration.getDefaultApiClient();
+        defaultClient.setBasePath("http://petstore.swagger.io:80/v2");
+
+        FakeApi apiInstance = new FakeApi(defaultClient);
+        Map<String, String> requestBody = new HashMap(); // Map<String, String> | request body
+        try {
+            apiInstance.testStringMapReference(requestBody);
+        } catch (ApiException e) {
+            System.err.println("Exception when calling FakeApi#testStringMapReference");
+            System.err.println("Status code: " + e.getCode());
+            System.err.println("Reason: " + e.getResponseBody());
+            System.err.println("Response headers: " + e.getResponseHeaders());
+            e.printStackTrace();
+        }
+    }
+}
+```
+
+### Parameters
+
+
+| Name | Type | Description  | Notes |
+|------------- | ------------- | ------------- | -------------|
+| **requestBody** | [**Map&lt;String, String&gt;**](String.md)| request body | |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+- **Content-Type**: application/json
+- **Accept**: Not defined
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | successful operation |  -  |
+