Hi There!

My OpenStack provider only supports FWaaS v2.0 and the v1.0 endpoint is disabled. Since v1.0 is also flagged as deprecated, Gophercloud should support the new FWaaS v2.0 endpoint:

https://developer.openstack.org/api-ref/network/v2/index.html#fwaas-v2-0-current-fwaas-firewall-groups-firewall-policies-firewall-rules

Cheers,
Christian