"Revert" PR #57

[jonpryor]

We need to better understand why AndroidVersions.KnownVersions needs to be public, because making it public is almost certainly the wrong thing to do, long-term.

In particular, the PR message is incorrect:

KnownVersions should be the only place we modify when new versions are published.

This is wrong; see also commit aad97f1. The intention is that xamarin-android should control which versions are "supported," via the presence of the AndroidApiInfo.xml files. Using the AndroidApiInfo.xml files is key, so that we can plausibly introduce new API levels (API-Q, anyone?) without requiring code changes to xamarin-android-tools (and the requisite product bumps across 6+ repos).

In short, what is the actual need behind PR #57?

For Android Manifest we also need to know what exists because Minimum Android Version and Target may be anything

This is in fact not correct either; there are limitations. Case in point: dotnet/android@06e920c.

NDK r19 -- which xamarin-android/master is now using -- has a minimum API level of 16...which varies across ABI targets. armeabi-v7a and x86 have a minimum API level of 16, while arm64-v8a and x86_64 have minimum API levels of 21. Trying to use a lower value may work, but it's highly likely they won't work, because of e.g. native linker symbol references.

In any event, anything prior to API-16 won't be QA'd or supported.

Which is a long-winded way of saying that this problem space is more complicated, and we need to come up with a more complete (and updatable!) solution.

Just making AndroidVersions.KnowVersions public Is Not The Correct Approach.