title: cannot insert null in one to many relationship hibernate annotation
body: <p>I have a class A{Set b .....} which holds references of class B as Set. It is one to many relationship.
  Both class have sequencer in oracle. I put cascade to all in hibernate annotations. When i save class A, it gives me error that cannot insert null B.a_id . A-id is not nullable in my database. How can i persist this relationship.</p>