{
  "endpoint": "createCreditNote",
  "description": "Unbekannter Grund",
  "request": {
    "idempotencyKey": "ex-12",
    "invoiceId": "invoice_example",
    "reason": "storno",
    "items": [
      {
        "description": "Nachlass",
        "quantity": 1,
        "unitPriceCents": 5000,
        "vatRate": 20
      }
    ]
  },
  "expected": {
    "ok": false,
    "code": "validation",
    "fields": [
      "reason"
    ]
  }
}