@Override
    public void request(int numMessages) {
        // The request of unary call is not reactive. `startDeframing()` will push the request message to
        // the stub through `listener.onMessage()` after `listener.onReady()` is invoked.
    }
Encapsulates the state of a single server call, reading messages from the client, passing to business logic
via {@link Listener}, and writing messages passed back to the response.
grpc/src/main/java/com/linecorp/armeria/server/grpc/UnaryServerCall.java