Major Description
With a backlog of messages on N destinations that exceeds the prefetch of the composite consumer for N, it is possible for dispatch on one destination to find the subscription full with messages from the other destinations.
If there are no pending messages for that destination it won't get an ack and hence won't attempt to dispatch again till there is another send. Leading to stalled pending messages.
The solution is to have a subscription wakeup all destination it is subscribed to once its dispatch list is exhausted.