@UnstableApi
    public VirtualHostBuilder serviceWorkerGroup(EventLoopGroup serviceWorkerGroup,
                                                 boolean shutdownOnStop) {
        this.serviceWorkerGroup = requireNonNull(serviceWorkerGroup, "serviceWorkerGroup");
        if (shutdownOnStop) {
            shutdownSupports.add(ShutdownSupport.of(serviceWorkerGroup));
        }
        return this;
    }
Sets the {@link EventLoopGroup} dedicated to the execution of services' methods.
If not set, the work group of the belonging channel is used.

@param shutdownOnStop whether to shut down the {@link EventLoopGroup} when the
                      {@link Server} stops
core/src/main/java/com/linecorp/armeria/server/VirtualHostBuilder.java