How to upgrade and install IAP 3.0 for Unity 2019?

Where is the documentation for upgrading and or adding IAP 3.0 for Unity 2019? I'm currently using IAP v2.0.6 and v2.2.2 with Unity 2019.3.11.f1. I'm not having any luck attempting to upgrade to the latest and cannot find any documentation beyond the following snippet.

- IAPProductCatalog.json and BillingMode.json are already in the resource folder.
- AppleTangle and GooglePlayTangle files do not exist in my project, nor does the "Assets/Plugins/UnityPurchasing/generated" folder.
- I then removed the unity purchase plugin folder and removed the In App Purchase package from package manager.

Now what? Where do I get 3.0? The service windows has the option to "Reimport" but doesn't appear to fix anything. It re-creates Plugins/UnityPurchasing folder with a bunch of ObseleteFilesOrDir.csv and meta files. All IAP purchase code fails to compile due to missing namespaces "IStoreController, IExtesnionsProvider, IGooglePlayStoreExtension" etc.

 

Finally figured it out.

- Followed the steps above for what was applicable. Results in missing namespaces but that's expected after removing everything.
- Then add the latest version in the package manager with the "Add package from git URL" option using the following address "com.unity.purchasing@3.1.0".

Not sure why the only place I could find this URL was in the release post for 2.2.8 but got the job done. No compile errors and appears to work fine so far on desktop. Will test mobile in the next few days.