We are running into a unique problem where when we update a username in Jira, Service Management is unaware of the change and create a new user.
Example:
Change username in jira of USER1 to BEST_USER1
Service desk syncs and see's that USER1 no longer exists, makes that user inactive and creates a new user with a new user_key for BEST_USER1 in the APP_USER table.
This makes the user lose all history in Service desk.