Cloned from launchpad blueprint https://blueprints.launchpad.net/keystone/+spec/email-attribute. Description: Email is a common attribute of users, and we already explicitly support this in keystoneclient, as well as show it in the entity examples in the Identity API specification. We also support mapping to it in our LDAP backend driver. However, we do not list it as supported attribute in the user resource specification. Specification URL (additional information): None