CodeOwnerConfigValidator: Log cause if validation fails

It was the assumption that this is not needed since the thrown
StorageException should be logged, but this seems to be not always the
case.

Signed-off-by: Edwin Kempin <ekempin@google.com>
Change-Id: I71047cd079f13486ad9c7048561e72a66825b827
diff --git a/java/com/google/gerrit/plugins/codeowners/validation/CodeOwnerConfigValidator.java b/java/com/google/gerrit/plugins/codeowners/validation/CodeOwnerConfigValidator.java
index f0023ff..86a206b 100644
--- a/java/com/google/gerrit/plugins/codeowners/validation/CodeOwnerConfigValidator.java
+++ b/java/com/google/gerrit/plugins/codeowners/validation/CodeOwnerConfigValidator.java
@@ -319,7 +319,7 @@
               "failed to validate code owner config files in revision %s"
                   + " (project = %s, branch = %s)",
               revCommit.getName(), branchNameKey.project(), branchNameKey.branch());
-      logger.atSevere().log(errorMessage);
+      logger.atSevere().withCause(e).log(errorMessage);
       throw new StorageException(errorMessage, e);
     }
   }