public class MessageGroupQueue
A BlockingQueue that is backed by a MessageGroupStore. Can be used to ensure guaranteed delivery in
the face of transaction rollback (assuming the store is transactional) and also to ensure messages are not lost if
the process dies (assuming the store is durable). To use the queue across process re-starts, the same group id
must be provided, so it needs to be unique but identifiable with a single logical instance of the queue.