@Override
    public void serviceAdded(ServiceConfig cfg) throws Exception {
        final VirtualHost defaultVirtualHost = cfg.server().config().defaultVirtualHost();
        if (this.defaultVirtualHost == defaultVirtualHost) {
            // This condition is necessary because:
            // - The same decorator can be added multiple times.
            // - Avoid infinite loop. The delegate of `decorator` is this.
            return;
        }
        this.defaultVirtualHost = defaultVirtualHost;
        decorator.serviceAdded(cfg);
    }
Adds the specified {@code prefix} to this {@code decorator}.
core/src/main/java/com/linecorp/armeria/internal/server/RouteDecoratingService.java