@mention Notification for Comments on Restricted Page in Confluence 5.4.x

In Confluence 5.4.x versions, the user is getting comment notifications in a page that he's restricted to view. If you restrict an user to view or edit the page through 'Tools > Restrictions' and then comment in a page, the user will get the notification about it in the Workbox.

Steps to Reproduce:

1. In a page go to 'Tools > Restrictions'
2. Allow only the creator/administrator to view the page
   
3. Comment mentioning an user in that page
4. Login with the mentioned user
5. Check the comment notification
   
6. By accessing the page, you don't have permissions to see it
   

This case seems to be related/a regression of CONFDEV-17188 which was affecting the mention in a page. However, for this one, it's caused only by mentions in comments. Also looks similar as JRA-29354 which is affecting JIRA.

Note that it only happens with Confluence 5.4.x versions. Other versions doesn't even display the notification for the user. For both the page and the comments.