code: public static Class<? extends Channel> getClientChannelClass(boolean isDomainSocket,
        AlluxioConfiguration conf) {
      ChannelType userChannelType = getUserChannel(conf);
      if (isDomainSocket) {
        Preconditions.checkState(userChannelType == ChannelType.EPOLL,
            "Domain sockets are only supported with EPOLL channel type.");
        return EpollDomainSocketChannel.class;
      }
      switch (userChannelType) {
        case NIO:
          return NioSocketChannel.class;
        case EPOLL:
          return EpollSocketChannel.class;
        default:
          throw new IllegalArgumentException("Unknown io type: " + userChannelType);
      }
    }
docs: Returns the correct {@link io.netty.channel.socket.SocketChannel} class for use by the client.
  
  @param isDomainSocket whether this is to connect to a domain socket server
  @param conf Alluxio configuration
  @return Channel matching the requirements