Merge branch 'stable-2.15' into stable-2.16

* stable-2.15:
  Upgrade mockito-core to 2.25.0
  Upgrade bazlets to latest stable-2.15
  Upgrade bazlets to latest stable-2.14
  Update bazlets to fix build with bazel 0.23

Change-Id: Ie8543e350e6849753f75b1c6f2a59ffcbf69de26