Golang golang.org/x/oauth2 400s :-(

I’m struggling to get an OAuth 3LA flow working.

This post was helpful but I’m clearly missing something.

Here’s my code:

I created an installed client and am passing DeviceID, ClientID and ClientSecret in through the environment. I only get 400s ({"code": 400}) from api.particle.io/oauth/authorize.

https://api.particle.io/oauth/authorize?access_type=offline&client_id=${ClientID}&response_type=code&scope=&state=Uv38ByGCZU8WP18PmmIdcpVmx00QA3xNe7sEB9Hixkk%3D

What am I doing wrong?