Steps to reproduce:
- Click on "Forgot your username?" on the login screen
- Open http://<server>/xwiki/bin/view/XWiki/ForgotUsername and add both a valid email associated to an user and an invalid email
Result: the platform confirms if the user exists or not.
Expected result: a generic message concerning the user without confirming if it exists or not (e.g. "If the account is registered on the application, you will receive a dedicated message").