public static void setEventLoopConfig(Configuration conf, EventLoopGroup group,
    Class<? extends Channel> channelClass) {
    Preconditions.checkNotNull(group, "group is null");
    Preconditions.checkNotNull(channelClass, "channel class is null");
    conf.set(EVENT_LOOP_CONFIG, CONFIG_NAME);
    EVENT_LOOP_CONFIG_MAP.put(CONFIG_NAME,
      Pair.<EventLoopGroup, Class<? extends Channel>> newPair(group, channelClass));
  }
Set the EventLoopGroup and channel class for {@code AsyncRpcClient}.
hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/NettyRpcClientConfigHelper.java