anchor.diff:  --------------------------------------------------
   int numRequests = 10;
   final CountDownLatch latch = new CountDownLatch(numRequests);
  +
   for (int i = 0; i < numRequests; i++) {
       restClient.performRequestAsync(
           "PUT",
  
positive.code:         }
      );
  }
  //wait for all requests to be completed
  latch.await();
  
  
negative.code:         "    \"post_date\" : \"2009-11-15T14:12:12\",\n" +
          "    \"message\" : \"trying out Elasticsearch\"\n" +
          "}", ContentType.APPLICATION_JSON);
  
  Response indexResponse = restClient.performRequest(
          "PUT",
          "/twitter/tweet/1",
          Collections.<String, String>emptyMap(),
          entity);
  --------------------------------------------------
  
  IMPORTANT: The `ContentType` that you specify for the `HttpEntity` is important
  because it will be used to set the `Content-Type` header so that Elasticsearch
  can properly parse the content. Future releases of Elasticsearch will require this
  to be set properly.
  
  Note that the low-level client doesn't expose any helper for json marshalling
  and un-marshalling. Users are free to use the library that they prefer for that
  