@Override
    public DefaultServiceConfigSetters serviceWorkerGroup(int numThreads) {
        final EventLoopGroup workerGroup = EventLoopGroups.newEventLoopGroup(numThreads);
        return serviceWorkerGroup(workerGroup, true);
    }
A default implementation of {@link ServiceConfigSetters} that stores service related settings
and provides a method {@link DefaultServiceConfigSetters#toServiceConfigBuilder(Route, String, HttpService)}
to build {@link ServiceConfigBuilder}.
core/src/main/java/com/linecorp/armeria/server/DefaultServiceConfigSetters.java