[pjmlp]

They didn't fully merged OpenJDK, just selected parts of it, across multiple Android versions.

Compatibility is still kind of broken.

It isn't possible to guarantee that any random Java library is usable on Android.

[agibsonccc]

Yes not all of it - there are still android specific bits yet. Enough of it is openjdk though.

[pjmlp]

And given how updates work....