Should I use the object returned from em.merge()

Question

I am still confused how to use em.merge() correctly. I need to know if I should use the result of em.merge().
PersistentObject obj = new PersistentObject();
obj.setSomething("Value#1");
// Should I do this and continue to use the object returned from merge().
obj = em.merge(obj);
obj.setSomething("Value#2");

Answer 1

Chris,
First thanks for your and your teams awesome support.
The reason I always get confused with merge() is my misunderstanding about how clones and caching are handled. Let me give you 2 scenerios and could you tell me what the problems are, is any?
Scenerio #1: (using return from merge)
-- Start of Transaction #1
EntityObject obj = new EntityObject();
obj.setName("chris");
obj = em.merge(obj);
-- End of Transaction #1
-- Start of Transaction #2
obj.setName("scott");
obj = em.merge(obj);
-- End of Transaction #2
Is this ok, will I lose data, are the clones and cache ok?
Scenerio #2: (NOT using return from merge)
-- Start of Transaction #1
EntityObject obj = new EntityObject();
obj.setName("chris");
em.merge(obj);
-- End of Transaction #1
-- Start of Transaction #2
obj.setName("scott");
em.merge(obj);
-- End of Transaction #2
Is this ok, ?
These 2 scenerios are different in the fact that one uses the return from merge and one does not. Which one is correct, and what would the problem be with the wrong one?