curl --request GET \
  --url https://api.meetcampfire.com/rr/api/v1/contracts/{contract_id}/usage \
  --header 'Authorization: <api-key>'

{
  "count": 123,
  "results": [
    {
      "id": 123,
      "contract": 123,
      "product_bundle": "<string>",
      "contract_product_bundle": {
        "id": 123,
        "source_bundle_name": "<string>",
        "total_amount": 0,
        "lines": [
          {
            "id": 123,
            "product": 123,
            "product_name": "<string>",
            "amount": 0,
            "percentage": "<string>",
            "original_percentage": 0
          }
        ],
        "source_bundle": 123,
        "currency": "<string>"
      },
      "product_name": "<string>",
      "product_bundle_name": "<string>",
      "usage_group_name": "<string>",
      "lines": "<string>",
      "created_at": "2023-11-07T05:31:56Z",
      "last_modified_at": "2023-11-07T05:31:56Z",
      "product": 123,
      "usage_group": 123,
      "department": 123,
      "tags": "<string>",
      "description": "<string>",
      "start_date": "2023-12-25",
      "end_date": "2023-12-25"
    }
  ],
  "next": "http://api.example.org/accounts/?offset=400&limit=100",
  "previous": "http://api.example.org/accounts/?offset=200&limit=100"
}