Please refer to Create File for more details about the multipart request format. The format
for Update File is the same, but the file part is optional. There are two modes for Updating a File object:

1. Upload a new file: both params and file parts are included
2. Modify the Octave File object only: only the params part is included

Uploading a new file will cause the File version to increment. The existing file will be preserved and accessible
using the Version API.

Modifying the Octave File object without uploading a file will not cause the version to increment.