AppStoreApi.GetSubscriptionAsync() does not support SIMPLE Product.Type

[alvaromarithompson]

SDK you're using (please complete the following information):

• Version 9.0.0

Describe the bug
When a subscription on the App Store contains a product whose pricing type is "Simple", retrieving any subscription that contains a product with "SIMPLE" pricing on it throws an exception on deserialization.

To Reproduce
Steps to reproduce the behavior:

1. Create a pricing plan that contains "Simple" pricing on it.
2. Subscribe to that plan via the App Store / Testing pages
3. Programmatically call AppStoreApi.GetSubscriptionAsync().
4. An exception is thrown:

Xero.NetStandard.OAuth2.Client.ApiException: 'Error converting value "SIMPLE" to type 'Xero.NetStandard.OAuth2.Model.Appstore.Product+TypeEnum'. Path 'plans[1].subscriptionItems[1].product.type', line 1, position 1536.'

Expected behavior
The subscription should be returned containing the relevant subscription item that has product of type SIMPLE

Screenshots
App Store pricing type:

Lack of definition of type "SIMPLE" in `Product.TypeEnum":

Additional context
The lack of Product.TypeEnum.SIMPLE can be seen at

Xero-NetStandard/Xero.NetStandard.OAuth2/Model/Appstore/Product.cs

Line 38 in 18684e2

public enum TypeEnum

[github-actions]

PETOSS-594

[github-actions]

Thanks for raising an issue, a ticket has been created to track your request

[alvaromarithompson]

The above bug is really the same complaint as #534 - New features are being introduced into core Xero products but their development team is not keeping the libraries up-to-date with their chosen enum mapping mechanism, thus causing things to break.

We've implemented a work around by not using the Xero.NetStandard library for retrieving subscriptions, instead relying on our own in-house REST library.