Merge branch 'stable-2.14' into stable-2.15

* stable-2.14:
  Format all build files with buildifier
  Update bazlets to latest stable-2.14 and adjust to 2.14.12 API
  Format all Java files with google-java-format
  Update bazlets to latest stable-2.14

This merge removes the username validation changes that were done for
compatibility with the 2.14.12 API, since this plugin's standalone
build is still building against the 2.15.2 API which doesn't have the
corresponding changes.

In a follow-up commit we should upgrade to use the 2.15.3-SNAPSHOT API
and make the necessary changes at the same time.

Change-Id: I6593dd8ecfa9eb3c708e919fca3463462cb60a17