{
  "endpoint": "issueInvoice",
  "description": "Die Rueckgabe-Wahl gehoert an die Gutschrift, nicht an die Rechnung",
  "request": {
    "idempotencyKey": "ex-17",
    "priceMode": "gross",
    "serviceStart": "2026-10-01",
    "items": [
      {
        "description": "Roggenbrot",
        "quantity": 1,
        "unitPriceCents": 450,
        "vatRate": 10,
        "returnDisposition": "restock"
      }
    ]
  },
  "expected": {
    "ok": false,
    "code": "validation",
    "fields": [
      "items[0].returnDisposition"
    ]
  }
}