code: @Test public void testChildrenListener() throws InterruptedException {
    String path="/dubbo/org.apache.dubbo.demo.DemoService/providers";
    zkclientZookeeperClient.create(path,false);
    final CountDownLatch countDownLatch=new CountDownLatch(1);
    zkclientZookeeperClient.addTargetChildListener(path,new IZkChildListener(){
      @Override public void handleChildChange(    String s,    List<String> list) throws Exception {
        countDownLatch.countDown();
      }
    }
  );
    zkclientZookeeperClient.createPersistent(path + "/provider1");
    countDownLatch.await();
  }
  