The code in UpgradeManager is broken. It silently ignores any upgrade task class that cannot be instantiated and moves on :
See the capture exception, log and move on. This THROWS the faulty upgrade task OUT Of the set, eg never puts in in there, and then the system will happily run all other stuff.
This is a major liability to JIRA. Data upgrades are the "assurance" that your systems data is in a well known and consistent state.
This issue is to capture JUST the changes need in UpgradeManagerImpl