problem

If a user is completly deleted, this deletes also the associations to a task.

But in that case no workflow functions are triggered, the deletion of the task user assoc is done directly in the DB.

solution

1. implement TRANSLATE-1563
2. Check workflow consistency on user deletion for the associated tasks. If the delete would result in a non consitence workflow, prohibit deletion
   1. Possibility one: delete the user in DB transaction, check consistency, if this is not the case, reject the transaction and throw a not deletable exception
   2. Possibility two: run the same SQL as for TRANSLATE-1563 - excluding the userGuid to be deleted - this simulates the consitency check with deleted user