code: public static String post(String url, Integer timeout)
        throws IOException {
      final StringBuilder contentBuffer = new StringBuilder();
      post(url, timeout, inputStream -> {
        try (BufferedReader br = new BufferedReader(
            new InputStreamReader(inputStream, "UTF-8"))) {
          String line;
          while ((line = br.readLine()) != null) {
            contentBuffer.append(line);
          }
        }
      });
      return contentBuffer.toString();
    }
docs: Uses the post method to send a url with arguments by http, this method can call RESTful Api.
  
  @param url the http url
  @param timeout milliseconds to wait for the server to respond before giving up
  @return the response body stream as UTF-8 string if response status is OK or CREATED