am a43be879: Merge change 4689 into donut

Merge commit 'a43be8798e54a208b4b06e0e30c7311d8711dd5d'

* commit 'a43be8798e54a208b4b06e0e30c7311d8711dd5d':
  Update the API of ApkBuilder to make it clearer what is stable and what isn't.