https://github.com/openstack/cinder/blob/bcea359d54fcaa5a013204f7981f952e4329cf93/cinder/api/v3/volumes.py#L329..L332

https://github.com/openstack/cinder/blob/bcea359d54fcaa5a013204f7981f952e4329cf93/cinder/api/views/backups.py#L47-L55

Create a volume from a backup is supported since 3.47 microversion, or since Queens: https://docs.openstack.org/cinder/latest/contributor/api_microversion_history.html#id44