public void testInterface() throws Exception {
OpenJPAEntityManager newEm =
(OpenJPAEntityManager) factory.createEntityManager();
startTx(newEm);
CacheObjectA a = (CacheObjectA) newEm.find(CacheObjectA.class, oid);
CacheObjectC c = new CacheObjectC("blah");
a.setRelatedInterface(c);
endTx(newEm);
Object cId = newEm.getObjectId(c);
endEm(newEm);
newEm = (OpenJPAEntityManager) factory.createEntityManager();
a = (CacheObjectA) newEm.find(CacheObjectA.class, oid);
CacheObjectInterface c2 = a.getRelatedInterface();
assertNotNull(c2);
assertEquals(cId, newEm.getObjectId(c2));
}