@Bean
    @ConditionalOnMissingBean(WebsocketDataChangedListener.class)
    public DataChangedListener websocketDataChangedListener() {
        return new WebsocketDataChangedListener();
    }
@Test
    public void testWebsocketDataChangedListener() {
        WebSocketSyncConfiguration websocketListener = new WebSocketSyncConfiguration();
        assertNotNull(websocketListener.websocketDataChangedListener());
    }