How to pass Encrypted characteristics into triggerPairing ( ) for Nearby interaction GATT Service

I am working on the background mode of nearby interaction, from the WWDC 2022 video, my Apps have to do pairing, connect with third party device's BLE Afterward, I have to implement a method called

triggerPairing ( peripheral: peripheral, encryptedCharacteristics: CBCharacteristics), 

to trigger pairing process.

The document mention that Apps should NOT discover the nearby interaction GATT service, but the encrypted characteristic is belonged to this service. how can I pass the parameters into the triggerPairing function if the Apps does not discover the service? what parameter should I pass into the function?

Does anyone help?