Im trying to upload an image for my broadcast using snippet.thumbnails object, my curl line is:
curl -X POST -H "Content-Type: application/json" -H "Authorization: Bearer $token" -d '{"snippet":{ "title":"test","description":"test desc","scheduledStartTime":"2018-09-25T20:35:48+0300","thumbnails": {"maxres": { "url": "https://static-cdn.jtvnw.net/img.png"}}},"status": {"privacyStatus": "public"}}' https://www.googleapis.com/youtube/v3/liveBroadcasts?part=snippet,status
when the broadcast is created image of it does not changed :( also I've tried to use default, medium, and high keys of thumbnails object and it does not help me :(