code: public static EventLoopGroup getServerBizEventLoopGroup(ServerTransportConfig config, Executor executor) {
          int bizThreads = config.getBizMaxThreads();
          return config.isUseEpoll() ?
              new EpollEventLoopGroup(config.getBizMaxThreads(), executor) :
              new NioEventLoopGroup(bizThreads, executor);
      }
docs: 得到服务端业务线程池
  
  @param config   服务端配置
  @param executor 业务线程池
  @return 服务端业务线程池