@Nullable
    public <T extends HttpService> T as(ServiceRequestContext ctx, Class<T> serviceClass) {
        final Queue<HttpService> delegates = ctx.attr(DECORATOR_KEY);
        if (delegates == null) {
            return null;
        }

        for (HttpService delegate : delegates) {
            final T service = delegate.as(serviceClass);
            if (service != null) {
                return service;
            }
        }
        return null;
    }
Adds the specified {@code prefix} to this {@code decorator}.
core/src/main/java/com/linecorp/armeria/internal/server/RouteDecoratingService.java