The PCEnhancer makes non entity classes "persistence aware", but we never explain what that means in the manual.
The answer can be found in the JDO specification, but we should document it in our manual as well. Many users may not be familiar with JDO or OpenJPA's JDO background. To those users the warning message issued by the PCEnhancer can be confusing, or a cause for alarm.
As a first pass we should add this information to the users manual. It would also be good to improve the logging of the PCEnhancer. In most cases the warning message is harmless, and should be treated as an INFO message (or better yet, we can issue a single message that lists all the persistence aware classes).