How to implement "play next" feature in just_audio?

Question

I'm trying to implement a "play next"/"add to queue" feature in my app. This is what I currently have:

final ConcatenatingAudioSource _queue = ConcatenatingAudioSource();

Future<void> addNextToQueue(String url) async {
  await _queue!.insert(
    _player.nextIndex!,
    AudioSource.uri(...),
  );
}

This approach works only if shuffle mode is disabled, otherwise track gets added somewhere else. How can I fix that?

Other solutions I've tried for _queue!.insert first argument were:

_player.currentIndex! + 1
_player.effectiveIndices![_player.nextIndex!]