'Update generic volume group.'

@proxy.logger
def update_group(self, ctxt, group, add_volumes, remove_volumes):

    grp = Group(group)
    if (grp.consisgroup_snapshot_enabled or grp.consisgroup_replication_enabled):
        self._assert((not grp.failed_over), ('Group    %s    has    been    failed    over,    it    does    not    support    to    update    it.' % grp.id))
        return self._update_consisgroup(grp, add_volumes, remove_volumes)
    else:
        raise NotImplementedError()
