subscribeToFeatureFlags method
Subscribes to the stream of feature flags and calls onEvent
when it
receives the list of feature flags.
Implementation
StreamSubscription subscribeToFeatureFlags(
void Function(List<BrazeFeatureFlag>) onEvent) {
StreamSubscription subscription =
featureFlagsStreamController.stream.listen(onEvent);
// Give any existing feature flags
getAllFeatureFlags().then((ffs) => onEvent(ffs));
return subscription;
}