@Override
  public void close() {
    childNetworkClients.values().forEach(NetworkClient::close);
    Utils.shutDownExecutorService(executor, 1, TimeUnit.MINUTES);
  }
@param childNetworkClients a map from {@link ReplicaType} to {@link NetworkClient} to use for that type.
ambry-network/src/main/java/com/github/ambry/network/CompositeNetworkClient.java