Enable DataObserver to observe T?, not only List<T>

I came across the DataObservers today and noticed, that when you call subscribe on a Query<T>, you will end in a List<T> as result which in my opinion is not what you want, e.g. if you want to find an entity by its id BUT also want to track the changes of this object, you would normally do this: boxStore.boxFor(T::class.java).query {}.findFirst() which would result in a T? result type. Now when i also want to track changes here, i wrap it in a flow (i use kotlin) like this:

@ExperimentalCoroutinesApi
fun <T> Query<T>.asFlow() = callbackFlow {
    val subscription =
        this@asFlow.subscribe()
            .onError { cancel("Database error", it) }
            .observer { data -> offer(data) }
    awaitClose { subscription.cancel() }
}

Suddenly i have to deal with a List<T> due to the fact, that the SubscriptionBuilder returns a SubscriptionBuilder<List<T>>.

Please add a more precise way to differ between single and multiple values. Currently i need to implement workarounds for this, but that should be a standard behaviour

まず Query.subscribe、DataObserver、SubscriptionBuilder を調べて、現在の subscription が List の結果を公開している理由を理解し、次にその動作を Query.findFirst() および Kotlin の asFlow の例と比較します。既存の複数結果の監視動作を維持しながら、単一の nullable な T を監視する方法が文書化されて提供されれば完了です。