protected static extern void RegisterOnUnsubscribedDelegate(OnUnsubscribedDelegate callback);
/// <summary>
/// Is called to subscribe a method to on unsubscribe event.
/// </summary>
/// <param name="callback">Method to subscribe.</param>
public void SubscribeToOnUnsubscribedEvent(OnUnsubscribedDelegate callback)
{
onUnsubscribedEvent += callback;
}
