public ServerBuilder workerGroup(EventLoopGroup workerGroup, boolean shutdownOnStop) {
        this.workerGroup = requireNonNull(workerGroup, "workerGroup");
        shutdownWorkerGroupOnStop = shutdownOnStop;
        return this;
    }
public ServerBuilder workerGroup ( EventLoopGroup workerGroup , boolean shutdownOnStop ) { this . workerGroup = requireNonNull ( workerGroup , "workerGroup" ) ; shutdownWorkerGroupOnStop = shutdownOnStop ; return this ; }
Sets the worker {@link EventLoopGroup} which is responsible for performing socket I/O and running
{@link Service#serve(ServiceRequestContext, Request)}.
If not set, {@linkplain CommonPools#workerGroup() the common worker group} is used.

@param shutdownOnStop whether to shut down the worker {@link EventLoopGroup}
when the {@link Server} stops