'Create and store a mapping to a public_id.
:param dict local_entity: Containing the entity domain, local ID and
type (\'user\' or \'group\').
:param public_id: If specified, this will be the public ID.  If this
is not specified, a public ID will be generated.
:returns: public ID'

@abc.abstractmethod
def create_id_mapping(self, local_entity, public_id=None):

    raise exception.NotImplemented()
