code: @Override
      public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException {
          String stackTrace = getStackTrace(baseRequest);
          if (stackTrace != null) {
              response.getWriter().print(getStackTrace(baseRequest));
          } else {
              super.handle(target, baseRequest, request, response);
          }
      }
docs: INSTANCE SCOPE ==========================================================