code: public static void sendAppUnavailableException(HttpServletRequest req, HttpServletResponse res) throws IOException {
          
          if ((req instanceof SRTServletRequest) && (res instanceof SRTServletResponse)) {
              IRequest ireq = ((SRTServletRequest) req).getIRequest();
              IResponse ires = ((SRTServletResponse) res).getIResponse();
              sendUnavailableException(ireq, ires);
          }
      }
docs: and throw a NPE because we couldn't get the application's configuration