post
https://api.sandbox.eu.ppro.com/v1/disputes//files
Upload a file to a dispute as multipart/form-data when the UPLOAD_FILE capability is allowed.
The file part must contain raw binary data (for example PDF or image bytes). Base64-encoded file content is not supported, including when indicated via Content-Transfer-Encoding: base64. Omit Content-Transfer-Encoding or use binary.
Set an appropriate Content-Type on the file part, such as application/pdf or image/png.