am 8a6310d0: am 2f8d7a9f: Merge change 21036 into donut

Merge commit '8a6310d0e5a284007cbf81a4f260b019366045af'

* commit '8a6310d0e5a284007cbf81a4f260b019366045af':
  Also display error on empty minSdkVersion for preview targets.