What's the rationale for NOT throwing ObjectDeletedException (or StaleObjectException) when you pass an object with an identifier that was deleted in a previous transaction to Session.merge()?

Just think about the usual CRUD interface: User 1 loads the object for modifications; User 2 deletes the object; User 1 saves the modifications (thru Session.merge). Now, instead of getting an exception, the object will be recreated. This is not desirable -- there was a concurrent modification, and User 1 should get a StaleObjectException or a ObjectDeletedException (not sure about which one is more appropriate -- my vote would go for the latter).

The javadoc for the merge operation says it's semantics are defined by JSR-220, which says:

"If X is a removed entity instance, an IllegalArgumentException will be thrown by the merge operation (or the transaction commit will fail)."

While I won't argue about the stupidness of throwing IAE instead of defining a more specific exception, the (unfinished, I know) specification makes it clear that calling merge() on deleted instances must fail, and not recreate the instance.