code: public void post(String url, HttpResponse response, Map<String, Object> headers, File file) {
          HttpPost methodPost = new HttpPost(url);
          HttpEntity multipart = buildBodyWithFile(file);
          methodPost.setEntity(multipart);
          getResponse(url, response, methodPost, headers);
      }
docs: Posts file as 'application/octet-stream'.
  @param url URL of service
  @param response response pre-populated with request to send. Response content and
  statusCode will be filled.
  @param headers http headers to add
  @param file file containing binary data to post.