[java] improve petstore tests with openapi v3 spec (#16447)

* regenerate tests in jersey2-java8 client

* update samples

* fix java google api client tests

* update java resteasy to use v3 spec for tests

* update java vertx to test with v3 spec

* update java resttemplate to test with v3 spec

* add new files

* regenerate jersey1 tests

samples/client/petstore/java/resteasy/docs/DefaultApi.md

@@ -0,0 +1,69 @@
+# DefaultApi
+
+All URIs are relative to *http://petstore.swagger.io:80/v2*
+
+| Method | HTTP request | Description |
+|------------- | ------------- | -------------|
+| [**fooGet**](DefaultApi.md#fooGet) | **GET** /foo |  |
+
+
+
+## fooGet
+
+> FooGetDefaultResponse fooGet()
+
+
+
+### 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.DefaultApi;
+
+public class Example {
+    public static void main(String[] args) {
+        ApiClient defaultClient = Configuration.getDefaultApiClient();
+        defaultClient.setBasePath("http://petstore.swagger.io:80/v2");
+
+        DefaultApi apiInstance = new DefaultApi(defaultClient);
+        try {
+            FooGetDefaultResponse result = apiInstance.fooGet();
+            System.out.println(result);
+        } catch (ApiException e) {
+            System.err.println("Exception when calling DefaultApi#fooGet");
+            System.err.println("Status code: " + e.getCode());
+            System.err.println("Reason: " + e.getResponseBody());
+            System.err.println("Response headers: " + e.getResponseHeaders());
+            e.printStackTrace();
+        }
+    }
+}
+```
+
+### Parameters
+
+This endpoint does not need any parameter.
+
+### Return type
+
+[**FooGetDefaultResponse**](FooGetDefaultResponse.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+- **Content-Type**: Not defined
+- **Accept**: application/json
+
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+| **0** | response |  -  |
+