KeyAttestation in Android Nougat API 24

问题:

I read about the new key attestation API in Android N and wanted to test it but I'm missing some classes.

The key attestation is described here: https://developer.android.com/preview/features/key-attestation.html

In the first code snipped a Attestation class is used which can't be found with the targetAPI set to API 24.

Attestation hardwareKeyAttestation = new Attestation(attestationCert);

Do I miss here anything? Do I need proprietary libraries?