code: protected void showApplicationExceptionHandling(ActionRuntime runtime, RuntimeException cause, ActionResponse response) {
          logAppEx(cause, () -> {
              // not show forwardTo because of forwarding log later
              final StringBuilder sb = new StringBuilder();
              buildAppExHeader(sb, runtime, cause, response);
              buildAppExStackTrace(sb, cause, 0);
              buildAppExFooter(sb);
              return sb.toString();
          });
      }
docs: =============