Hello, I followed the steps at: https://developers.strava.com/docs/webhookexample/
I got a callback when I requested it this morning

but return 400 reason is strava request parameter 'hub.mode' for method parameter type String is not present
i change this

@RequestParam(value = "hub.mode", required = false) String mode

however when i push_subscriptions again. I never received callback from strava again。it remain “GET to callback URL does not return 200”. I also tried calling the endpoint directly