Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  Set Gerrit to 2.16.21
  Set Gerrit to 2.15.19
  Set Gerrit to 2.14.21
  Set version to 2.16.20

Change-Id: I1546035daae9cc22ced0921a37026d7fdc5bc9fe