class SubnetTopologyController < TopologyController
  @layout = "subnet_topology"
  @service_class = SubnetTopologyService
end

class SubnetTopologyController < TopologyController
  @layout = "subnet_topology"
  # @service_class = SubnetTopologyService
end

Comment out SubnetTopologyService from SubnetTopologyController
Comment out SubnetTopologyService from SubnetTopologyController

The class SubnetTopologyService isn't defined anywhere and this line
would cause parsing error for gettext model attribute extraction task.
