Google Apps Script issue with headers

Question

The SEC Edgar website requires only 1 item in the header...but I can't get it to work in Script...What am I doing wrong?

Script:
const options = {
'method' : 'get',
'contentType' : 'application/json',
headers: {"User-Agent": "first last [email protected]"}}

Here's a good place to test that this header is all that is required...
https://reqbin.com/req/5nqtoxbx/get-json-example
All you have to do is change the header.

SEC's info on this is limited at best: https://www.sec.gov/os/accessing-edgar-data