file.deleteOnExit();
            }
        }
    }

    private ChecksumObserver addChecksumObserver(Wagon wagon, String algorithm) throws TransferFailedException {
        try {
            ChecksumObserver checksumObserver = new ChecksumObserver(algorithm);
            wagon.addTransferListener(checksumObserver);
            return checksumObserver;
        } catch (NoSuchAlgorithmException e) {