Virtual peers can be starved on Grouping tasks

[MichaelDrogalis]

This is a particularly rough edge case. If a virtual peer receives a grouping task, it's capable of being starved from receiving the sentinel segment off the queue due to the way that HornetQ pins messages as it groups. If a consumer closes out, it might not necessarily requeue the sentinel in a server node where other consumers can reach it. Hence, the other virtual peers may deadlock and wait forever. This only affects batch mode - streaming mode is fine.

[MichaelDrogalis]

Closing, dropping HornetQ support next release.