code: @Override
    public String getTrackingUrl() {
      if (this.httpServer == null) {
        return "";
      }
  
      try {
        return InetAddress.getLocalHost().getHostAddress() + ":" + httpServer.getPort();
      } catch (final UnknownHostException e) {
        LOG.log(Level.WARNING, "Cannot get host address.", e);
        throw new RuntimeException("Cannot get host address.", e);
      }
    }
docs: get tracking URI.
  
  @return