Dry-run variant of create(CloudRouterCreatorJson): POSTs the same body to
/fabric/v4/routers with dryRun=true - per the Fabric v4 spec, an
"option to verify that API calls will succeed".
Dry-run variant of create(CloudRouterCreatorJson): POSTs the same body to
/fabric/v4/routers with dryRun=true - per the Fabric v4 spec, an
"option to verify that API calls will succeed". Nothing is provisioned; the API responds
200 with the validated request echoed back (no uuid/href/state).