code: public static void useNioTransport(NettyServerBuilder builder) {
      builder.channelType(NioServerSocketChannel.class);
      builder
          .bossEventLoopGroupPool(SharedResourcePool.forResource(Utils.NIO_BOSS_EVENT_LOOP_GROUP));
      builder
          .workerEventLoopGroupPool(
              SharedResourcePool.forResource(Utils.NIO_WORKER_EVENT_LOOP_GROUP));
    }
docs: Sets {@link io.grpc.Channel} and {@link io.netty.channel.EventLoopGroup}s to Nio. A major
  benefit over using existing setters is gRPC will manage the life cycle of {@link
  io.netty.channel.EventLoopGroup}s.