Does AVAudioSessionCategoryOptionAllowBluetooth change audio route to BluetoothHFP?

Hi I'm adding Bluetooth functionality to my app.

I've set audio session category to AVAudioSessionCategoryPlayAndRecord

and give options AVAudioSessionCategoryOptionMixWithOthers and AVAudioSessionCategoryOptionAllowBluetooth, and AVAudioSessionCategoryOptionAllowBluetoothA2DP.

And when I got AVAudioSessionRouteChangeNotification, currentRoute value was changed to BluetoothHFP automatically.

Is this by design?

If it is, how can I rollback BluetoothHFP route to orignal one(BluetoothA2DP)?

I tried to use setPreferredInput to 'Built-In Microphone' but setPreferredInput changed output route to 'Reciever' too.