code: public void doHttpFilePost(String url, HttpResponse result, Map<String, Object> headers, File file) {
          httpClient.post(url, result, headers, file);
      }
docs: Performs POST to supplied url of a file as binary data.
  @param url url to post to.
  @param result result containing request, its response will be filled.
  @param headers headers to add.
  @param file file containing binary data to post.