我已经写了这个函数来从S3中获取对象，现在我想写单元测试用例。我无法模拟“s3Client.getObjectAsynchronous（objectRequest）”，因此我可以获得“ResponseAsynchronous objectRequest”的模拟响应并继续。

GetObjectRequest objectRequest = GetObjectRequest
                .builder()
                .key(keyName)
                .bucket(bucketName)
                .build();

        ResponseBytes<GetObjectResponse> objectBytes = s3Client.getObjectAsBytes(objectRequest);
        LOGGER.info(objectBytes.toString());
        InputStream inputStream = objectBytes.asInputStream();
        String result = new BufferedReader(new InputStreamReader(inputStream))
                .lines().collect(Collectors.joining("\n"));
        LOGGER.info(result);