curl --request POST \
  --url https://api.metronome.com/v1/composite/createCustomerWithContract \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "customer": {
    "name": "Example, Inc.",
    "ingest_aliases": [
      "team@example.com"
    ]
  },
  "contract": {
    "starting_at": "2020-01-01T00:00:00.000Z"
  }
}
'

{
  "data": {
    "customer_id": "d7abd0cd-4ae9-4db7-8676-e986a4ebd8dc",
    "ingest_aliases": [
      "team@example.com"
    ],
    "customer_name": "Aperture, Inc.",
    "contract_id": "7aa11640-0703-4600-8eb9-293f535a6b74"
  }
}