Merge branch 'stable-3.7' into stable-3.8

* stable-3.7:
  Deleting a project that has no entry shouldn't cause a split brain
  Fix compilation error for missing variable
  Fix CompileTimeConstant ErrorProne issue

Change-Id: Ib5f2475eca9a5f28c62e48c5c2ef5583ea157ead

src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java
index 0aa0c9f..db8f30a 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/validation/dfsrefdb/zookeeper/ZkSharedRefDatabase.java
@@ -30,6 +30,7 @@
 import org.apache.curator.framework.recipes.atomic.DistributedAtomicValue;
 import org.apache.curator.framework.recipes.locks.InterProcessMutex;
 import org.apache.curator.framework.recipes.locks.Locker;
+import org.apache.zookeeper.KeeperException;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
 
@@ -89,6 +90,8 @@
   public void remove(Project.NameKey project) throws GlobalRefDbSystemError {
     try {
       client.delete().deletingChildrenIfNeeded().forPath("/" + project);
+    } catch (KeeperException.NoNodeException e) {
+      logger.atWarning().log("Project '%s' not found in Zookeeper", project);
     } catch (Exception e) {
       throw new GlobalRefDbSystemError(
           String.format("Not able to delete project '%s'", project), e);