loginUser

Log in the user whose credentials are currently stored in the credentials store. If there are no stored user credentials, this method will create a new user via the UserCenterManager and then log in the newly created user. If the email domain is different in the existing user credentials from the one that was provided for this instance, a new email with the new domain will be generated and the old email will be replaced.

Return

A task which will resolve to valid Session instance.