Did they? The only thing which comes to mind is the mandatory "Billboard Class" support for USB-C adapters, which allows them to inform the device they're atta

Did they? The only thing which comes to mind is the mandatory "Billboard Class" support for USB-C adapters, which allows them to inform the device they're attached to that negotiation has failed. But that's not really anything physical on the adapter itself, it's essentially a super-simple read-only micro flashdrive.