curl --request POST \
  --url https://api.maesn.dev/accounting/files \
  --header 'Content-Type: multipart/form-data' \
  --header 'X-ACCOUNT-KEY: <x-account-key>' \
  --header 'X-API-KEY: <x-api-key>' \
  --form contactId=287a382-s35e624e5-fb9e-483 \
  --form documentDate=2021-01-01T00:00:00Z \
  --form documentId=b5e624e5-fb9e-4836-a443-87a3820f5b48 \
  --form documentType=Ausgangsrechnung \
  --form 'integrationSource=Third party app' \
  --form 'note=Invoice 02-03-2023' \
  --form file=@example-file

{
  "meta": {
    "warnings": [
      "Field not used by target system"
    ],
    "pagination": {
      "total": 123,
      "perPage": 123,
      "currentPage": 123,
      "totalPages": 123
    }
  },
  "data": {
    "id": "document id",
    "base64Encoded": true,
    "content": "content",
    "contentType": "application/pdf",
    "fileName": "invoice.pdf"
  }
}