What replaces AkMediaAsset in Wwise 2022?

Question

I'm trying to upgrade our Wwise/UE integration from 2021 to 2022.1.1.8100, and I see a lot of custom code (implemented by the old audio programmer before I joined), that makes use of external sources by way of AkMediaAsset.h. Since this file appears to no longer exist, what's the new API/method for handling external sources?