Function handle_connection 

async fn handle_connection<Client>(
    stream: TcpStream,
    peer: SocketAddr,
    fhir_client: Arc<Client>,
    config: Arc<ReceiverConfig>,
)
where
    Client: FHIRClient<(), OperationOutcomeError> + Send + Sync + 'static,

Serves one sender until it disconnects, idles out, or breaks framing.