'List users in a group.
:param str group_id: the group in question
:param hints: filter hints which the driver should
implement if at all possible.
:type hints: keystone.common.driver_hints.Hints
:returns: a list of users or an empty list. See user schema in
:class:`~.IdentityDriverBase`.
:rtype: list of dict
:raises keystone.exception.GroupNotFound: If the group doesn\'t exist.'

@abc.abstractmethod
def list_users_in_group(self, group_id, hints):

    raise exception.NotImplemented()
