public  void onLock(LockEvent event) throws HibernateException 
{
		if ( event.getObject() == null ) {
			throw new NullPointerException( "attempted to lock null" );
		}
		if ( event.getLockMode() == LockMode.WRITE ) {
			throw new HibernateException( "Invalid lock mode for lock()" );
		}
		SessionImplementor source = event.getSession();
		Object entity = source.getPersistenceContext().unproxyAndReassociate( event.getObject() );
		//TODO: if object was an uninitialized proxy, this is inefficient,
		//      resulting in two SQL selects
		EntityEntry entry = source.getPersistenceContext().getEntry(entity);
		if (entry==null) {
			final EntityPersister persister = source.getEntityPersister( event.getEntityName(), entity );
			final Serializable id = persister.getIdentifier( entity, source.getEntityMode() );
			if ( !ForeignKeys.isNotTransient( event.getEntityName(), entity, Boolean.FALSE, source ) ) {
				throw new TransientObjectException(
						"cannot lock an unsaved transient instance: " +
						persister.getEntityName()
				);
			}
			entry = reassociate(event, entity, id, persister);
			cascadeOnLock(event, persister, entity);
		}
		upgradeLock( entity, entry, event.getLockMode(), source );
}

Handle the given lock event.