Many of the jBPM tables use a single common sequence, HIBERNATE_SEQUENCE
. In addition, some of them reserve more than one sequence at a time to assign.
Given this, you will definitely not get sequential sequence IDs - I'm not certain why this is a requirement though. In addition, even if you were getting sequential sequences and there was a rollback, the sequence would have already been used and would then be lost.
jBPM6 has slightly more specific tables for sequences, but you'll still run into issues with roll-backs not generating sequential sequences.
You'll have to modify the source code yourself to change the IDs from being autogenerated to being manually populated - honestly though, it will probably be more effort than it's worth.