curl --request POST \
  --url https://app.herondata.io/api/end_users/{end_user_id_or_heron_id}/pdfs/v1 \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '{
  "account_id": "checking_account_202348",
  "currency": "USD",
  "filename": "my-favourite.pdf",
  "pdf_base64": "<string>",
  "read_us_dates": null,
  "reference_id": "my-favourite-pdf"
}'

{
  "pdf_heron_id": "<string>",
  "request_id": "<string>"
}