code: private static URL getDefaultAnnounceUrl(InetSocketAddress address) {
      try {
        return new URL("http",
                address.getAddress().getCanonicalHostName(),
                address.getPort(),
                ANNOUNCE_URL);
      } catch (MalformedURLException mue) {
        logger.error("Could not build tracker URL: {}!", mue, mue);
      }
  
      return null;
    }
docs: Returns the full announce URL served by this tracker.
  <p>
  <p>
  This has the form http://host:port/announce.
  </p>