Add details to validate/exception.

Fix bug b/261724375

Change-Id: I6a82c96ad58c87bc53268c18564ea7a202162889
diff --git a/libraries/automotive-helpers/notifications-app-helper/src/android/platform/helpers/AutoNotificationMockingHelperImpl.java b/libraries/automotive-helpers/notifications-app-helper/src/android/platform/helpers/AutoNotificationMockingHelperImpl.java
index 61b04ae..209eee9 100644
--- a/libraries/automotive-helpers/notifications-app-helper/src/android/platform/helpers/AutoNotificationMockingHelperImpl.java
+++ b/libraries/automotive-helpers/notifications-app-helper/src/android/platform/helpers/AutoNotificationMockingHelperImpl.java
@@ -130,7 +130,7 @@
         for (BySelector selector : NOTIFICATION_REQUIRED_FIELDS) {
             UiObject2 obj = findUiObject(selector);
             if (obj == null) {
-                throw new RuntimeException("Unable to find required notification field");
+                throw new RuntimeException(String.format("Unable to find required notification field %s",selector.toString()));
             }
         }
         return true;