code: public static String getContentPost(String stringUrl, Map<String, String> parameters,
            String input, String charset) throws IOException {
        return getContentPost(stringUrl, parameters, input, charset, false);
    }
docs: Post content / get response
  
  @param stringUrl URL to use
  @param parameters HTTP headers
  @param input Input data (payload)
  @param charset Charset in the input
  @return response HTTP response
  @throws IOException I/O error happened