curl --request POST \
  --url https://vantage-us.abbyy.com/api/publicapi/v1/transactions/{transactionId}/documents \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/*+json' \
  --data '
{
  "imageProcessingOptions": {},
  "index": "<string>"
}
'

{
  "documentId": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
}