hammer -u admin -p changeme subnet create --name DATA --network 192.168.0.0 --mask 255.255.255.0 --gateway 192.168.0.254 --dns-primary 192.168.1.1 --dns-secondary 192.168.1.2 --from 192.168.0.1 --to 192.168.0.253 --vlanid 2 --dhcp-id 1 --tftp-id 1 --domains foo.com
Could not create the subnet:
Subnet domains is invalid
Subnet domains is invalid

But this works :
hammer -u admin -p changeme subnet create --name DATA --network 192.168.0.0 --mask 255.255.255.0 --gateway 192.168.0.254 --dns-primary 192.168.1.1 --dns-secondary 192.168.1.2 --from 192.168.0.1 --to 192.168.0.253 --vlanid 2 --dhcp-id 1 --tftp-id 1
Subnet created
hammer -u admin -p changeme subnet update --name DATA --domains foo.com
Subnet updated

The first command used to work in foreman 1.10 and previous releases.