Map-Reduce: Mapper sometimes receives null value
ISPN-4471 MapReduceTask: memory leak with useIntermediateSharedCache = true
ISPN-4453 MapReduceTask#executeAsynchronously() isn't asynchronous
ISPN-4137 Transaction executed multiple times due to forwarded CommitCommand

Make rollback commands synchronous
Move stuff from AbstraceEnlistmentAdapter to TransactionCoordinator.