code: public static String httpPost (URL url, String submission, int timeout)
          throws IOException, ServiceWaiter.TimeoutException
      {
          return httpPost(url, submission, timeout,
              Collections.singletonMap("Content-Type", "application/x-www-form-urlencoded"));
      }
docs: Return the results of a form post. Note that the http request takes place on another
  thread, but this thread blocks until the results are returned or it times out. This
  overload sets a single request property of
  <code>"Content-Type" = "application/x-www-form-urlencoded"</code>.
  
  @param url from which to make the request.
  @param submission the entire submission eg {@code foo=bar&baz=boo&futz=foo}.
  @param timeout time to wait for the response, in seconds, or -1 for forever.