@Override
            public File call() throws Exception {
                try {
                    for (Future<Long> future : futures) {
                        future.get();
                    }

                    download.setState(Transfer.TransferState.Completed);
                } finally {
                    FileLocks.unlock(dstfile);
                }

                return dstfile;
            }
Returns a Callable to execute {@link AmazonS3#download(PresignedUrlDownloadRequest)} with given request.
aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/transfer/internal/PresignUrlDownloadCallable.java