How do you send Pubsub Whisper from EBS?

Extensions
5

Thanks, The API is accepting the Post with status code 204 (undefined). But the listening client user’s aren’t getting a message.

I’m using these for my JWT:
(edit: userId below is decodedToken.opaque_user_id)
(edit 2: find working code below)

{
   ...
    "role": "external",
    "channel_id": "whisper-" + userId,
    "pubsub_perms": { "send":[ "whisper-*" ] } 
};

And in the body:

{
    ....
    "targets": [ "whisper-" + userId]
}

Posting to:

 'https://api.twitch.tv/extensions/message/whisper-'+ userId

And the client listening like this:

window.Twitch.ext.onAuthorized(function(auth) {
    ...
    window.Twitch.ext.listen("whisper-" + auth.userId, function(target, contentType, message){
        console.log("Hello World");
    });
});

Any help getting this to work would be appreciated.