primary property
A copy of the "primary" CryptoKeyVersion that will be used by Encrypt when this CryptoKey is given in EncryptRequest.name.
The CryptoKey's primary version can be updated via UpdateCryptoKeyPrimaryVersion. Keys with purpose ENCRYPT_DECRYPT may have a primary. For other keys, this field will be omitted.
Output only.
Implementation
CryptoKeyVersion? primary;