public Function<? super HttpService, AuthService> newDecorator() {
        final Authorizer<HttpRequest> authorizer = authorizer();
        return delegate -> build(delegate, authorizer);
    }
Returns a newly-created decorator that decorates an {@link HttpService} with a new
{@link AuthService} based on the {@link Authorizer}s added to this builder.
core/src/main/java/com/linecorp/armeria/server/auth/AuthServiceBuilder.java