private InstanceType extractServiceInstance(
      PathChildrenCacheEvent event, ChildData childData) {
    byte[] data = childData.getData();
    if (data == null) return null;
    try {
      ServiceRecord srv = encoder.fromBytes(event.getData().getPath(), data);
      return createServiceInstance(srv);
    } catch (IOException e) {
      LOG.error("Unable to decode data for zknode: {}." +
          " Dropping notification of type: {}", childData.getPath(), event.getType());
      return null;
    }
  }
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