How PolicyCenter updates ExCheckTime

Any time a batch process runs exception rules on a given PolicyPeriod entity, the process does the following:

1. It runs the exception rules on the PolicyPeriod.
2. It finds the PolicyPeriod entity’s associated PolicyException entity, or it creates a PolicyException entity if it does not find one.
3. It sets PolicyException.ExCheckTime to the current system clock time.
4. It saves (commits) the changes to the database.