protected static byte[] getWorkerData(ChildData childData, String workerNodePrefix) {
    if (childData == null) return null;
    byte[] data = childData.getData();
    if (data == null) return null;
    if (!isLlapWorker(extractNodeName(childData), workerNodePrefix)) return null;
    return data;
  }
Get the ensemble server addresses from the configuration. The format is: host1:port,
host2:port..

@param conf configuration
llap-client/src/java/org/apache/hadoop/hive/registry/impl/ZkRegistryBase.java