How to catch OptimisticLockException in servlet level?

I'm using JPA toplink-essential, building REST web app.

I have a servlet that find one entity and delete it.

Below code I thought I could catch optimistic lock exception in servlet level but its not! Instead RollbackException is thrown, and that's what documentation says:

But then when I see the Netbean IDE GlassFish log, somewhere, optimisticLockException is thrown. It's just not being caught in my code. (my system print message doesn't get displayed so I'm sure its not going in there.)

I tried to import each packages (one at a time of course) and tested with catch clause but both time, it is not going into the catch block even though log error says "optimistic exception".

import javax.persistence.OptimisticLockException;
import oracle.toplink.essentials.exceptions.OptimisticLockException;

So where the OptimisticLockException is thrown?????

@Path("delete")
@DELETE
@Consumes("application/json")
public Object planDelete(String content) {

   try {
            EntityManager em = EmProvider.getInstance().getEntityManagerFactory().createEntityManager();

            EntityTransaction txn = em.getTransaction();
            txn.begin();
            jObj = new JSONObject(content);
            MyBeany bean = em.find(123);

            bean.setVersion(Integer.parseInt(12345));
            em.remove(bean);


            //here commit!!!!!
            em.getTransaction().commit(); 
        }
        catch(OptimisticLockException e) {  //this is not caught here :(
            System.out.pritnln("here");
            //EntityTransactionManager.rollback(txn);
            return HttpStatusHandler.sendConflict();
        }
        catch(RollbackException e) {
            return HttpStatusHandler.sendConflict();
        }
        catch(Exception e) {
            return HttpStatusHandler.sendServerError(e);
        }
        finally {
            if(em != null) {
                em.close();
            }
        }

Error msg:

[TopLink Warning]: 2011.01.28 05:11:24.007--UnitOfWork(22566987)
--Exception [TOPLINK-5006] 
(Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): 
oracle.toplink.essentials.exceptions.OptimisticLockException

    [TopLink Warning]: 2011.02.01 08:50:15.095--UnitOfWork(681660)--
javax.persistence.OptimisticLockException: Exception [TOPLINK-5006] (Oracle TopLink 
Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): 
oracle.toplink.essentials.exceptions.OptimisticLockException

Not 100% sure, but could it be that you're catching javax.persistence.OptimisticLockException (notice the package), but as the thrown exception is oracle.toplink.essentials.exceptions.OptimisticLockException, it's not getting caught? Even though the name of exception-class is the same, they're not the same class.