AppCheckToken
A token the App Check backend issues once it has attested the app, mirroring com.google.firebase.appcheck.AppCheckToken.
The Android SDK's class is Java, so Android code subclasses it by overriding getToken and getExpireTimeMillis, for the tokens of an AppCheckProvider of its own, and reads the getters as the properties token and expireTimeMillis. Both compile here as well, with one difference: those two properties are declared here, so a subclass cannot declare properties of its own with these names (private val token in the constructor of a subclass needs another name, such as value).
Properties
When the token expires, in milliseconds since the epoch: getExpireTimeMillis.
Functions
Destructures an AppCheckToken: its AppCheckToken.token.
Destructures an AppCheckToken: its AppCheckToken.expireTimeMillis.
Returns when the token expires, in milliseconds since the epoch.