Calculate hash of digests

public static String calculateGroupHash(Set<String> digests) {
    BigInteger hash = BigInteger.valueOf(0);
    for (String entry : digests) {
        try {
            BigInteger digest = new BigInteger(Hex.decodeHex(entry.toCharArray()));
            hash = hash.xor(digest);
        } catch (DecoderException e) {
            e.printStackTrace();
        }
    }
    return Hex.encodeHexString(hash.toByteArray());
}