EJB3 - inherited @Id primary key not found

Hi folks,

In case anyone is curious, I've found that almost every EJB3 
implementation I've tried so far has peculiarities:

- Hibernate EntityManager in standalone (no app server) mode works great;
- I couldn't get anything to work in GlassFish b48, there were lots of 
seemingly bogus TOPLink exceptions in its log;
- Most things work fine in JBoss 4 (after all, it uses Hibernate 
EntityManager), but it still uses Tomcat as its web container, so I 
can't use @PersistenceUnit in a JSP, and I'm trying to avoid JNDI;
- One of Resin's pecularities is the subject of this email. :)

I use an abstract superclass for all my persistent entities; Resin 
(unlike any other container) doesn't like this class to be mapped in 
persistence.xml, complaining that abstract classes can't be entities.  
But when I remove it, Resin complains that its subclasses don't have 
primary keys.

Is there a simple workaround?

Thanks!

-0xe1a