protected final void closeZooKeeper() {
    if (this.zooKeeper != null) {
      LOG.info("Close zookeeper");
      this.zooKeeper.close();
    }
  }
Sets the abort state if not already set.
@return True if abortRequested set to True successfully, false if an abort is already in
        progress.
hbase-server/src/main/java/org/apache/hadoop/hbase/HBaseServerBase.java