}
        sourceState.set(result);
        return result;
    }

    static String sha1(Path path) throws NoSuchAlgorithmException, IOException {
        MessageDigest md = MessageDigest.getInstance("SHA-1");
        try (InputStream fis = Files.newInputStream(path)) {
            byte[] buffer = new byte[SHA1_BUFFER_SIZE];
            int read;
            while ((read = fis.read(buffer)) != -1) {