pub fn new() -> Self {
        // According to the gRPC Health Check specification, the empty service "" corresponds to the overall server health
        let server_status = ("".to_string(), watch::channel(ServingStatus::Serving));

        let statuses = Arc::new(RwLock::new(HashMap::from([server_status])));

        HealthReporter { statuses }
    }
Create a new HealthReporter with an initial service (named ""), corresponding to overall server health
tonic-health/src/server.rs