Finer filter when subscribing to receive onDataChanged notifications

When subscribing to receive onDataChanged notification, it would be helpful if the subscriber could provide more details about what notifications they want to receive. For example, a Device Driver may want to be notified when a “Device-Type” augmentation is applied to an inventory node. It would be helpful if the Device Driver could specify that it only wants to be notified if a new Device-Type augmentation is applied and the augmentation value is equal to a specified value. The benefit of allowing the subscriber to more precisely specify when they want to be notified will reduce the number of notifications and therefore improve performance.