@Override
    public ServerBuilder decorator(
            Route route, Function<? super HttpService, ? extends HttpService> decorator) {
        virtualHostTemplate.decorator(route, decorator);
        return this;
    }
Decorates {@link HttpService}s with the specified {@link Route}.
The specified decorator(s) is/are executed in reverse order of the insertion.

@param route the route being decorated
@param decorator the {@link Function} that decorates {@link HttpService} which matches
                 the specified {@link Route}
core/src/main/java/com/linecorp/armeria/server/ServerBuilder.java