Group represents a referenceable set of Users
Identity records a successful authentication of a user with an identity provider. The information about the source of authentication is stored on the identity, and the identity is then associated with a single user object. Multiple identities can reference a single user. Information retrieved from the authentication provider is stored in the extra field using a schema determined by the provider.
UserIdentityMapping maps a user to an identity
Upon log in, every user of the system receives a User and Identity resource. Administrators may directly manipulate the attributes of the users for their own tracking, or set groups via the API. The user name is unique and is chosen based on the value provided by the identity provider - if a user already exists with the incoming name, the user name may have a number appended to it depending on the configuration of the system.