@Override
  public void nodeCreated(String path) {
    if (path.equals(labelZnode) || path.equals(userAuthsZnode)) {
      try {
        ZKUtil.watchAndCheckExists(watcher, path);
      } catch (KeeperException ke) {
        LOG.error("Error setting watcher on node " + path, ke);
        // only option is to abort
        watcher.abort("ZooKeeper error obtaining label node children", ke);
      }
    }
  }
A zk watcher that watches the labels table znode. This would create a znode
/hbase/visibility_labels and will have a serialized form of a set of labels in the system.
hbase-server/src/main/java/org/apache/hadoop/hbase/security/visibility/ZKVisibilityLabelWatcher.java