{
    if (isNotificationRequired())
    {
      boolean oldIsSet = isSet();
      NotificationImpl notification = createNotification(Notification.SET, doSetUnique(index, object), object, index, oldIsSet);
      if (notifications == null) 
      {
        notifications = notification;
      }
      else
      {
        notifications.add(notification);
      }
    }
    else
    {
      doSetUnique(index, object);
    }
    return notifications;
  }