Upload a file as a new Attachment and store it for this collectionWith large files or files stored at a document management system like SharePoint, we highly recommend using Add New Attachment Link This endpoint does not support a base64 encoded upload.For file upload we only support multipart/form-data.
Because oAuth is authenticated by a user, this is the user creating this attachment.
For integrations that are not user specific, customers are advised to create a separate user specifically for this integration.