@Bean
    @ConditionalOnMissingBean(EtcdDataDataChangedListener.class)
    public DataChangedListener etcdDataChangedListener(final EtcdClient etcdClient) {
        return new EtcdDataDataChangedListener(etcdClient);
    }
@Test
    public void testEtcdDataChangedListener() {
        EtcdSyncConfiguration etcdListener = new EtcdSyncConfiguration();
        EtcdClient client = mock(EtcdClient.class);
        assertNotNull(etcdListener.etcdDataChangedListener(client));
    }