private void notifyDataListeners() {
        if (newDataListeners == null) return;
        for (Tuple2<Runnable, Executor> listener : newDataListeners) {
            listener.second.execute(listener.first);
        }
    }
Gets and removes all the data currently available in this.
The returned list is a modifiable fresh instance owned by the caller.
container-core/src/main/java/com/yahoo/processing/response/DefaultIncomingData.java