A behaviour adapter module to be implemented by clients that using the Openstex library for handling Keystone Authentication.
Openstex
get_xauth_token(atom) :: String.t | no_return
identity(atom) :: Openstex.Keystone.V2.Helpers.Identity.t | no_return
start_link(atom) :: {:ok, pid} | {:error, :already_started}
start_link(atom, opts :: Keyword.t) :: {:ok, pid} | {:error, :already_started}