Build the slack-integration plugin on stable-2.16

Change-Id: I84252306a3671003276d5d5597b999b99c51e244
diff --git a/jenkins/gerrit-mvn-plugin-slack-integration.yaml b/jenkins/gerrit-mvn-plugin-slack-integration.yaml
index f3ec7bc..962fe81 100644
--- a/jenkins/gerrit-mvn-plugin-slack-integration.yaml
+++ b/jenkins/gerrit-mvn-plugin-slack-integration.yaml
@@ -3,8 +3,9 @@
     repo: slack-integration
     branch:
       - master
-      - stable-2.14
+      - stable-2.16
       - stable-2.15
+      - stable-2.14
       - stable-2.13
       - stable-2.12
       - stable-2.11