BUG:21187 put back hardcoded client without the issue created in 8484

Author: sushma3690

samples/client/petstore/java/feign-no-nullable/src/main/java/org/openapitools/client/ApiClient.java

@@ -29,6 +29,7 @@
 import feign.form.FormEncoder;
 import feign.jackson.JacksonDecoder;
 import feign.jackson.JacksonEncoder;
+import feign.okhttp.OkHttpClient;
 import feign.slf4j.Slf4jLogger;
 import org.openapitools.client.auth.HttpBasicAuth;
 import org.openapitools.client.auth.HttpBearerAuth;
@@ -53,11 +54,13 @@ public interface Api {}
   protected String basePath = "http://petstore.swagger.io:80/v2";
   protected Map<String, RequestInterceptor> apiAuthorizations;
   protected Feign.Builder feignBuilder;
+  private static final OkHttpClient OK_HTTP_CLIENT = new OkHttpClient();
 
   public ApiClient() {
     apiAuthorizations = new LinkedHashMap<String, RequestInterceptor>();
     objectMapper = createObjectMapper();
     feignBuilder = Feign.builder()
+                .client(OK_HTTP_CLIENT)
                 .encoder(new FormEncoder(new JacksonEncoder(objectMapper)))
                 .decoder(new ApiResponseDecoder(objectMapper))
                 .errorDecoder(new ApiErrorDecoder())