在SpeechGrpc上的Google云长语音识别返回空的Respose

Question

我正在尝试基于使用SpeechGrpc api的android应用示例（https://github.com/GoogleCloudPlatform/android-docs-samples/tree/master/speech/Speech）来执行longRunningRecognize，代码正在无异常运行，大约一分钟后，我得到了响应，但我得到了替代方法结果为空，尝试了几个文件，我将很高兴了解我在做什么错？ 代码：

private SpeechGrpc.SpeechStub mApi;
private OperationsGrpc.OperationsStub operationApi;

 public  void recognizeLongGcs(String gcsUri) throws Exception {        
    try  {            
        mApi.longRunningRecognize(LongRunningRecognizeRequest.newBuilder()
                .setConfig(
                RecognitionConfig.newBuilder()
                        .setEncoding(RecognitionConfig.AudioEncoding.FLAC)
                        .setLanguageCode("iw")
                        .setSampleRateHertz(16000)
                        .build())
                .setAudio( RecognitionAudio.newBuilder().setUri(gcsUri).build())
                                .build(),
                        mLongFileResponseObserver);             
    }
    catch (Exception e)
    {            AnalyticsModel.getInstance().logError(this.getClass().getSimpleName() , e   );
    }
}


private final StreamObserver<Operation> mLongFileResponseObserver
        = new StreamObserver<Operation>() {
    Operation response;
    String responseName;
    @Override
    public void onNext(Operation response) {
        String text = null;
        List<WordInfo> words = null;            
        responseName =response.getName();
        try {
            if (response.getDone())
            {
                Any a = response.getResponse();
                LongRunningRecognizeResponse longRunningRecognizeResponse  = LongRunningRecognizeResponse.parseFrom(a.getValue());
                final SpeechRecognitionResult result = longRunningRecognizeResponse.getResults(0);
                if (result.getAlternativesCount() > 0) {
                    final SpeechRecognitionAlternative alternative = result.getAlternatives(0);
                    text = alternative.getTranscript();
                    words = alternative.getWordsList();
                }
            }
            else {
                Thread.sleep(10000);
                operationApi.getOperation(GetOperationRequest.newBuilder().setName(responseName).build(), mLongFileResponseObserver);
            }
        }
        catch (Exception e) { }
    }

    @Override
    public void onError(Throwable t) {            
        Log.e(TAG, "Error calling the API.", t);
    }

    @Override
    public void onCompleted() {
        Log.i(TAG, "API completed.");            
    }

};