public void start() throws KeeperException {
    watcher.registerListener(this);
    ZKUtil.createWithParents(watcher, labelZnode);
    ZKUtil.createWithParents(watcher, userAuthsZnode);
    byte[] data = ZKUtil.getDataAndWatch(watcher, labelZnode);
    if (data != null && data.length > 0) {
      refreshVisibilityLabelsCache(data);
    }
    data = ZKUtil.getDataAndWatch(watcher, userAuthsZnode);
    if (data != null && data.length > 0) {
      refreshUserAuthsCache(data);
    }
  }
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