### Question:
WebSocketEndpoint { @OnError public void onError(Session session, Throwable error) { logger.error("webSocket: /webSocket/demo on Error, the session is {} ", session, error); }  @OnOpen void onOpen(Session session); @OnMessage void onMessage(String message, Session session); @OnClose void onClose(); @OnError void onError(Session session, Throwable error);  }### Answer:
@Test public void onError() { }