Serializable id = event.getRequestedId();
      if ( id == null ) {
         id = persister.getIdentifier( entity, source );
      }
      else {
         // check that entity id = requestedId
         Serializable entityId = persister.getIdentifier( entity, source );
         if ( !persister.getIdentifierType().isEqual( id, entityId, source.getFactory() ) ) {
            throw new HibernateException( "merge requested with id not matching id of passed entity" );
         }
      }

   /**
    * Handle the given update event.
    *
    * @param event The update event to be handled.
    */
   public void onSaveOrUpdate(SaveOrUpdateEvent event) {
      final SessionImplementor source = event.getSession();
      final Object object = event.getObject();
      final Serializable requestedId = event.getRequestedId();

   [b]   if ( requestedId != null ) {
         //assign the requested id to the proxy, *beforeQuery*
         //reassociating the proxy
         if ( object instanceof HibernateProxy ) {
            ( (HibernateProxy) object ).getHibernateLazyInitializer().setIdentifier( requestedId );
         }
      }[/b]

      // For an uninitialized proxy, noop, don't even need to return an id, since it is never a save()
      if ( reassociateIfUninitializedProxy( object, source ) ) {
         LOG.trace( "Reassociated uninitialized proxy" );
      }
      else {
         //initialize properties of the event:
         final Object entity = source.getPersistenceContext().unproxyAndReassociate( object );
         event.setEntity( entity );
         event.setEntry( source.getPersistenceContext().getEntry( entity ) );
         //return the id in the event object
         event.setResultId( performSaveOrUpdate( event ) );
      }

}