It would be beneficial to some users to be able to map the Liferay User Id to a custom field in LDAP or to allow log in by UUID. This would allow users to log in with a custom Id. One example use case to support this is when a user changes their name. In many cases, this means that the screen name and email address are changed as well. When this renamed user is imported into Liferay, they will be considered a new user. It would be helpful to log in with a unique custom Id to allow for cases like this.