I've uploaded files via "file request" web form, and its form requires an input mail address and comments. We can see its mail address as "Last updated by" and commetns as "Description" as below.

However, I cannot get its value via API :-(
$ curl -i -X GET "https://api.box.com/2.0/files/xxxxxxxxx" --header 'Authorization: Bearer xxxxx'
Executed it via curl, and get value like below.
"created_by":{"type":"user","id":"2","name":"Anonymous User","login":""},
"modified_by":{"type":"user","id":"2","name":"Anonymous User","login":""}
And no descriptions.
So question is, how to get its value that we can see with browser via API?