curl --request POST \
  --url https://{tenant}.fincode.software/api/v6/services/documentmanagement/attach-documents \
  --header 'Content-Type: application/json' \
  --header 'X-Auth-Token: <x-auth-token>' \
  --header 'platform: <platform>' \
  --header 'uuid: <uuid>' \
  --data '
{
  "customerCode": "CUST123456",
  "attachedDocument": [
    {
      "name": "proof_of_address.jpg",
      "idType": "PROOF_OF_ADDRESS",
      "file_base64": "base64EncodedStringOfYourFile..."
    }
  ]
}
'