Alexa java sdk：如何将歌曲排在onPlaybackNearlyFinished？ （AudioPlayer）

Question

我正在开发一种流式传输音频文件的Alexa技能。播放工作正常，甚至暂停，恢复和“getNextSong”正在工作，但我不能在第一个完成后排队。

这就是我调用我的方法来排队下一首歌的地方：

@Override 
public SpeechletResponse onPlaybackNearlyFinished(SpeechletRequestEnvelope<PlaybackNearlyFinishedRequest> requestEnvelope) {
logger.info("Playback nearly finished");
return queueNextSong(requestEnvelope); 
}

这是我的入队方法：

private SpeechletResponse queueNextSong(SpeechletRequestEnvelope<PlaybackNearlyFinishedRequest> requestEnvelope) {

SystemState state = requestEnvelope.getContext().getState(SystemInterface.class, SystemState.class);

UserSession userSession = null;

try {
    userSession = new DynamoDbService().getUserSession(state.getUser().getUserId());
} catch (Exception e) {
    logger.error("Unable to obtain userSession Object.");
}

String url = null;
// Don't worry about this line, i just use the last object of my songList because it's cheaper to remove than the first entry.
url = userSession.getSongQueue().get(userSession.getSongQueue().size()-1);

Stream stream = new Stream();
stream.setUrl(url);
stream.setOffsetInMilliseconds(0);
stream.setExpectedPreviousToken(requestEnvelope.getRequest().getToken());
stream.setToken(url);

AudioItem audioItem = new AudioItem();
audioItem.setStream(stream);

PlayDirective playDirective = new PlayDirective();
playDirective.setAudioItem(audioItem);
playDirective.setPlayBehavior(PlayBehavior.ENQUEUE);

List<Directive> directives = new ArrayList<>();
directives.add(playDirective);

SpeechletResponse response = new SpeechletResponse();
response.setDirectives(directives);
return response; 
}

我缺少什么？我需要一些帮助...我已经阅读了官方文档并检查了论坛，但没有一个解决方案正在运行。 :(我回复了错误的回答吗？错字？感谢任何帮助。