DomainAvailable is needed to check if an org domain is available before completing social sign-up.

IsAuthorized checks if the request has permission to perform the action.

ResetCredential resets a user's password to a specified value.

UpdateCredential updates a user's password to a specified valued.

TODO: remove.

Authenticated stores data about the authenticated user.

AuthorizationError indicates that the user who performed the operation does not have the required role.

RequestContext stores the http.Request, and values derived from the request like the authenticated user.

Response is accumulated by API endpoints and used for logging and reporting.