protected final ProtocolType getProxy(
      final LlapNodeId nodeId, final Token<TokenType> nodeToken) {
    String hostId = getHostIdentifier(nodeId.getHostname(), nodeId.getPort());
    LOG.debug("Getting host proxies for {}", hostId);
    try {
      return hostProxies.get(hostId, new Callable<ProtocolType>() {
        @Override
        public ProtocolType call() throws Exception {
          return createProxy(nodeId, nodeToken);
        }
      });
    } catch (ExecutionException e) {
      throw new RuntimeException(e);
    }
  }
@param nodeId Hostname + post.
@param nodeToken A custom node token. If not specified, the default token is used.
@return the protocol client implementation for the node.
llap-common/src/java/org/apache/hadoop/hive/llap/AsyncPbRpcProxy.java