Improve logging when catching a zookeeper error

Feature: Issue 12098
Change-Id: I9e01bb30cff2d19f0b48be07f310c51a63950b0c
diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidator.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidator.java
index 82d4ff0..e66b3ba 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidator.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/RefUpdateValidator.java
@@ -146,6 +146,11 @@
     try {
       succeeded = sharedRefDb.compareAndPut(projectName, refPair.compareRef, refPair.putValue);
     } catch (IOException e) {
+      logger.atWarning().withCause(e).log(
+          "Not able to persist the data in Zookeeper for project '{}' and ref '{}', message: {}",
+          projectName,
+          refPair.getName(),
+          e.getMessage());
       throw new SharedDbSplitBrainException(errorMessage, e);
     }