Empty response for stop point arrivals

The details for the the stop point “Liverpool street” is as follows:
“$type”: “Tfl.Api.Presentation.Entities.MatchedStop, Tfl.Api.Presentation.Entities”,
“icsId”: “1000138”,
“modes”: [
“zone”: “1”,
“id”: “HUBLST”,
“name”: “Liverpool Street”,
“lat”: 51.51794,
“lon”: -0.083162

When I use this URL for the arrival informations: https://api.tfl.gov.uk/StopPoint/HUBLST/Arrivals
I got an empty array back (like this “[]”).

Is this the correct URL for stop point arrivals?
Do I need to add ?Mode=XX&Line=XX ?
Do I need to append the api_key as well?

Thanks a lot

Not sure you can get Arrivals from a “HUB”.

Use the standard call - https://api.tfl.gov.uk/StopPoint/HUBLST - to get the various lineGroups (tube, overground, buses, tflrail) and make calls to each using the naptanIdReference provided…

You can call the APIs in parallel if your need the results quickly.