You should be getting this exception at runtime, right?
Basically, you are calling a getter on your 'associated' or 'many' instances after the transaction has been committed. Once a transaction is closed, or a Session that loaded the one side of the equation, is closed or committed, lazy objects from that relationship can no longer be loaded - the associated instances are really proxies or placeholders for real data, and that data was only accessible during the transaction that loaded the one side.
Don't commit your transaction so early, or you can call the associated objects before the transaction is committed.
Happy Hibernating!
-Cameron McKenzie