public ServerBuilder workerGroup(EventLoopGroup workerGroup, boolean shutdownOnStop) {
        this.workerGroup = requireNonNull(workerGroup, "workerGroup");
        // We don't use ShutdownSupport to shutdown with other instances because we shut down workerGroup first.
        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
core/src/main/java/com/linecorp/armeria/server/ServerBuilder.java