Integrating with OneSignal

When following the ( excellent! ) documentation for the OneSignal integration, it references the old methods of getting the device ID, which don’t exist since the OneSignal migration to their new `User Centric` model.
 

OneSignal.add(self as OSSubscriptionObserver) // No longer exists

// If you've already set up OneSignal, then users should already have
// a OneSignal Id. We can check if it's available and send it to RevenueCat
if let onesignalId = OneSignal.getUserDevice()?.getUserId() { // No longer exists
    Purchases.shared.attribution.setOnesignalID(onesignalId)
}

I’d love to know what I should be setting as the attribution ID using the new methods ( they’re not covered in the migration guide ), as trying the various IDs I can find results in the web hooks failing due to missing aliases, or invalid IDs, and the device ID is no longer accessible as far as I can tell

Thanks!