Actually, had the wrong variable name in location for x-api-key, so now I get the correct request header printed back to me

$ curl -i -H "x-api-key:somekey" -H "userAccount:someaccount" https://localhost/ --insecure
HTTP/1.1 200 OK
Server: nginx/1.10.3 (Ubuntu)
Date: Tue, 01 Jan 2019 17:30:28 GMT
Content-Type: application/octet-stream
Content-Length: 127
Connection: keep-alive

request: GET / HTTP/1.1; x-api-key: somekey; userAccount: someaccount

But the proxy still does not like what NGINX is sending vs. me sending it directly with curl.