Fix flogger format string

Change-Id: I765aaa0eb0869385c5d2aee6db1d28eb614836ae
diff --git a/src/main/java/com/gerritforge/gerrit/globalrefdb/validation/RefUpdateValidator.java b/src/main/java/com/gerritforge/gerrit/globalrefdb/validation/RefUpdateValidator.java
index 7fa5645..626067a 100644
--- a/src/main/java/com/gerritforge/gerrit/globalrefdb/validation/RefUpdateValidator.java
+++ b/src/main/java/com/gerritforge/gerrit/globalrefdb/validation/RefUpdateValidator.java
@@ -231,7 +231,7 @@
               Project.nameKey(projectName), refPair.compareRef, refPair.putValue);
     } catch (GlobalRefDbSystemError e) {
       logger.atWarning().withCause(e).log(
-          "Not able to persist the data in Zookeeper for project '{}' and ref '{}', message: {}",
+          "Not able to persist the data in Zookeeper for project '%s' and ref '%s', message: %s",
           projectName,
           refPair.getName(),
           e.getMessage());