nova/doc/api_samples/os-assisted-volume-snapshots/snapshot-create-assisted-resp.json

{
    "snapshot": {
        "id": "421752a6-acf6-4b2d-bc7a-119f9148cd8c",
        "volumeId": "521752a6-acf6-4b2d-bc7a-119f9148cd8c"
    }
}