전자(세금)계산서 수정발행 - 공급가액 변동

curl --request POST \
  --url https://xapi.bolta.io/v1/taxInvoices/{issuanceKey}/amend/changeSupplyCost \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "date": "2026-05-27",
  "taxType": "TAXABLE",
  "items": [
    {
      "date": "2026-05-27",
      "name": "가격 조정",
      "unitPrice": null,
      "quantity": null,
      "supplyCost": -200000,
      "tax": -20000,
      "specification": null,
      "description": null
    }
  ]
}
'