@Override
    public void close() throws IOException {
        ShutdownUtils.shutdownChannel(channel);
        ShutdownUtils.shutdownEventExecutor(eventExecutors);
        ExecutorUtils.shutdownAndAwaitTermination(workerExecutor, 3, TimeUnit.SECONDS);
    }
Construct client connecting to HelloWorld server at {@code host:port}.
agent-module/plugins-it/google-grpc-it/google-grpc-1-8-it/src/test/java/com/navercorp/pinpoint/it/plugin/grpc/HelloWorldStreamClient.java