code: protected void fireUnrecoverableError(UnrecoverableBackendErrorEvent e) {
          for (int i = 0, n = this.listenerList.size(); i < n; i++) {
              this.listenerList.get(i).unrecoverableErrorOccurred(e);
          }
      }
docs: Notifies all registered listeners when an unrecoverable error has
  occurred in a backend.
  
  @param e a {@link UnrecoverableBackendErrorEvent} representing the
  cause of the error.