cinder/api-ref/source/v3/samples/volume-type-default-response.json

{
    "volume_type": {
        "id": "6685584b-1eac-4da6-b5c3-555430cf68ff",
        "name": "volume-type-test",
        "description": "default volume type",
        "is_public": true,
        "extra_specs": {
            "volume_backend_name": "rbd"
        }
    }
}