Add a test for BigDecimal parameter in java client (#16263)

* add a test for BigDecimal parameter in java client

* update tests

samples/client/petstore/java/okhttp-gson/docs/AnotherFakeApi.md

@@ -5,6 +5,7 @@ All URIs are relative to *http://petstore.swagger.io:80/v2*
 | Method | HTTP request | Description |
 |------------- | ------------- | -------------|
 | [**call123testSpecialTags**](AnotherFakeApi.md#call123testSpecialTags) | **PATCH** /another-fake/dummy | To test special tags |
+| [**getParameterStringNumber**](AnotherFakeApi.md#getParameterStringNumber) | **GET** /fake/parameter-string-number | parameter string number |
 
 
 <a id="call123testSpecialTags"></a>
@@ -69,3 +70,62 @@ No authorization required
 |-------------|-------------|------------------|
 | **200** | successful operation |  -  |
 
+<a id="getParameterStringNumber"></a>
+# **getParameterStringNumber**
+> getParameterStringNumber(stringNumber)
+
+parameter string number
+
+### 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.AnotherFakeApi;
+
+public class Example {
+  public static void main(String[] args) {
+    ApiClient defaultClient = Configuration.getDefaultApiClient();
+    defaultClient.setBasePath("http://petstore.swagger.io:80/v2");
+
+    AnotherFakeApi apiInstance = new AnotherFakeApi(defaultClient);
+    BigDecimal stringNumber = new BigDecimal(78); // BigDecimal | string number
+    try {
+      apiInstance.getParameterStringNumber(stringNumber);
+    } catch (ApiException e) {
+      System.err.println("Exception when calling AnotherFakeApi#getParameterStringNumber");
+      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 |
+|------------- | ------------- | ------------- | -------------|
+| **stringNumber** | **BigDecimal**| string number | |
+
+### Return type
+
+null (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: Not defined
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **200** | OK |  -  |
+