Allowed Scopes: experimental:intake:write

Creates a presigned upload target for an intake file. This is step 1 of 3 in creating an intake from a document:

1. Create an upload with this endpoint to get a presigned URL and an uploadId.
2. Send the file to that URL, then poll Get an intake file upload status until it returns a documentId.
3. Pass that documentId to Create an intake.

contentLength must be the exact byte size of the file you are about to send. The presigned policy pins that size, so an approximate value makes the upload in step 2 fail rather than this call.

To send the file, make a multipart/form-data request to upload.url using upload.method. Include every entry of upload.fields as a form field, then add the file itself as a field named file, last. The URL points to our storage provider and not to the Spendesk API, so do not send your access token with it. Upload before upload.expiresAt; once the URL has expired, call this endpoint again for a fresh one.