code: @Override
    public int getPort(HttpServletRequest request) {
      String portValue = request.getHeader(X_FORWARED_PORT);
      if( portValue != null ) return Integer.parseInt(portValue);
      return super.getPort(request);
    }
docs: When the X-Forwarded-Port header is present, this method returns the value of that header.  When
  the header is not present, it delegates this call to the super class.