code: private Callable<S3Object> serviceCall(final PresignedUrlDownloadRequest presignedUrlDownloadRequest) {
          return new Callable<S3Object>() {
              @Override
              public S3Object call() throws Exception {
                  return s3.download(presignedUrlDownloadRequest)
                           .getS3Object();
              }
          };
      }
docs: Returns a Callable to execute {@link AmazonS3#download(PresignedUrlDownloadRequest)} with given request.