pub fn add_service<S>(mut self, svc: S) -> Self
    where
        S: Service<Request<Body>, Error = Infallible>
            + NamedService
            + Clone
            + Send
            + Sync
            + 'static,
        S::Response: axum::response::IntoResponse,
        S::Future: Send + 'static,
    {
        self.routes = self.routes.add_service(svc);
        self
    }
Add a new service to this router.
tonic/src/transport/server/mod.rs