Inappstore plugin support for refund notifications via didRevokeEntitlementsForProductIdentifiers

[PseudoC0de]

This would fall under 'enhancement'.

Right now there is no way to receive/process refund notifications. This would allow an easy way for devs to make any changes in the event that a user refunds a consumable or non-consumable in-app product.

Documentation: https://developer.apple.com/documentation/storekit/skpaymenttransactionobserver/3564804-paymentqueue?language=objc