The acknowledge() method on a session acknowledged all messages fetched thus far.
Some applications wish to acknowledge messages after themselves receiving some asynchronous confirmation of processing. This limitation prevents such applications from operating fully asynchronously as they cannot acknowledge any message until processing of all fetched messages has been confirmed to them.
Added ability to acknowledge a specific message
Applications who wish to tie acknowledgements to asynchronous confirmations they themselves receive on successful processing of the messages can now do so.