@Override
    public ServerBuilder decorator(
            String pathPattern, Function<? super HttpService, ? extends HttpService> decorator) {
        virtualHostTemplate.decorator(pathPattern, decorator);
        return this;
    }
Decorates {@link HttpService}s whose {@link Route} matches the specified {@code pathPattern}.
The specified decorator(s) is/are executed in reverse order of the insertion.
core/src/main/java/com/linecorp/armeria/server/ServerBuilder.java