liveActivityToken property
Apple Live Activity token to send updates to.
This token can either be a push token or
[push-to-start](https://developer.apple.com/documentation/activitykit/activity/pushtostarttoken)
token from Apple. To start, update, or end a live activity remotely using
FCM, construct an [aps payload
](https://developer.apple.com/documentation/activitykit/starting-and-updating-live-activities-with-activitykit-push-notifications#Construct-the-payload-that-starts-a-Live-Activity)
and put it in the
[apns.payload
](https://firebase.google.com/docs/reference/fcm/rest/v1/projects.messages#ApnsConfig)
field.
Optional.
Implementation
core.String? liveActivityToken;