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

@param decorator the {@link Function} that decorates {@link HttpService}s
core/src/main/java/com/linecorp/armeria/server/ServerBuilder.java