JiraSession: Add missing @Override annotation

Change-Id: I6fba895048008c033f12ae6b7dcd13ca3d1d85ae
diff --git a/src/main/java/com/googlesource/gerrit/plugins/its/jira/JiraSession.java b/src/main/java/com/googlesource/gerrit/plugins/its/jira/JiraSession.java
index 2609ddf..bdc62fa 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/its/jira/JiraSession.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/its/jira/JiraSession.java
@@ -33,6 +33,7 @@
     return token;
   }
 
+  @Override
   public String toString() {
     return "username="+username+", token="+token;
   }