What happens if this propriety “user.requireEmailAsUsername” is changed to true, does any body know the rules?
Like for example do you need to delete the user that haven’t email as username? or even has super user does it have to follow the rule, and have a email on username?
It should be able to allow any username if the property is set to false, you might want to look at the logs to confirm what is invalid, could be something else.