How to create an Android custom MediaCas plugin?

Question

I'm trying to add an Android custom MediaCas plugin but it's not clear how to do handle that. The MediaCas.Session appears to be a final class and can't be extended.

Any documentation, example code or open source code that demonstrate how to create it ?

I see under this link two example plugins:

• clearkey
• mock

https://github.com/LineageOS/android_frameworks_av/tree/489bfc236b5639f869850784d4122d7cd4f191b2/drm/mediacas/plugins

but it's not clear how to integrate in an app or elsewhere.