Merge branch 'stable-3.1'

* stable-3.1:
  Fix bazlets using latest stable-3.1 to build with 3.1.5 API
  Use Gerrit 3.1.5 in Dockerfile
  Use Gerrit 3.0.9 in Dockerfile
  Use Gerrit 2.16.19 in Dockerfile
  Upgrade bazlets to latest stable-3.1 to build with 3.1.5 API
  Upgrade bazlets to latest stable-3.0 to build with 3.0.9 API
  Upgrade bazlets to latest stable-2.16 to build with 2.16.19 API

Change-Id: Ifdf3c41ef74a0ffdbc346967cbe5f002ef96c245
diff --git a/src/test/docker/gerrit/Dockerfile b/src/test/docker/gerrit/Dockerfile
index 689d2b7..bfce2c4 100644
--- a/src/test/docker/gerrit/Dockerfile
+++ b/src/test/docker/gerrit/Dockerfile
@@ -1,4 +1,4 @@
-FROM gerritcodereview/gerrit:3.1.4
+FROM gerritcodereview/gerrit:3.1.5
 
 ENV GERRIT_BRANCH=stable-3.1