Get primary key from persistent bean

[Dain Sundstrom]

Is there a way to extract the primary key from a persistent bean  
using a spec JPA API or an API specific to OpenJPA?  I'm thinking of  
something like this:

    MyBean bean = new MyBean();
    entityManager.persist(bean);
    Object pk = entityManager.getPrimaryKey(bean);
    MyBean foundBean = entityManager.find(MyBean.class, pk);
    assertEquals(bean, foundBean);
-dain