Hue Emulation: Expose a group as a room

I’d like to expose some rooms on my emulated Hue Bridge, but I can’t figure out how to do that.
When I access /api/testuser/groups, The API only returns an auto-generated “All Lights” group.
The addon documentation only says “Rooms: Maps to group items with a specific tag” but I can’t find any information anywhere what those “specific tags” are.

I even looked at the source code and found a code snippet in, line 166, that looks for tags starting with huetype_ and hueroom_. Tried to add those (with a suffix obviously) to my group, but it didn’t help.

// Restore group type and room class from tags
for (String tag : g.getTags()) {
    if (tag.startsWith("huetype_")) {
        group.type = tag.split("huetype_")[1];
    } else if (tag.startsWith("hueroom_")) {
        group.roomclass = tag.split("hueroom_")[1];

// ...

cs.ds.groups.put(hueID, group);

How do I do this? The official Hue app doesn’t seem to let me control my lights without putting them into a room first, and trying to create a room in the app fails. Thanks!

The hueemulation binding was never intended to work with the official Hue app.

The binding is there to trick Alexa or the Harmony Hub into believing that “real” Hue devices are being used here.