code: protected boolean checkExists(String path) {
          try {
              return client.checkExists().forPath(path) != null;
          } catch (Exception e) {
              throw new NiubiException(e);
          }
      }
docs: 检查该节点是否存在
  
  @param path 节点路径
  @return 如果存在返回true,否则为false