Tthat would add a lot of latency.
We could do this automatically after current message has been processed (in aroundReceive), but I'm not sure. It  might be important to be explicit about this. `addDelivery` updates the internal state, i.e. is also supposed to be done during recovery (as well as `confirm`), while `sendAddedDeliveries` is performing external side effects, and is supposed to be done here (only).