Merge branch 'stable-3.1' into stable-3.2

* stable-3.1:
  Upgrade Gerrit API to 3.1.15
  Update Gerrit API to 3.0.16
  Update Gerrit API to 2.16.27
  Upgrade Gerrit API to 3.1.12
  Update Gerrit API to 3.0.15
  Update Gerrit API to 2.16.26

Change-Id: I02c39e8e0d5e55f7d7386985fed0784d5cf68f2b