The request body must include a FileUpload object in application/json format.

For customer-level documents, provide FCCID and file.

For account-specific documents, provide FCCID, FCAID, and file so the document is linked to the customer account.

The nested file object must include name and contentType. Metadata fields like description, source, and tags are optional. helpdesk is also optional and defaults to true; set it to false when the uploaded document should not be visible in the customer portal.