Foreman Version: 1.23
Ruby Version: 2.3.3

Description:

Creating a subnet parameter via API results in error "unknown attribute 'organization_id' for SubnetParameter".

How to reproduce:

1. create a subnet
2. issue the following post request:
https://<foreman>/api/v2/subnets/<id>/parameters
payload: {
"parameter": {
"name": "my_param",
"value": "my_value",
"parameter_type": "string"
}
}

Same happens if "organization_id": "" is added to payload.