@Override
    public int hashCode() {
        if (this.bytes == null || this.bytes.length == 0) {
            return 0;
        }
        return Arrays.hashCode(this.bytes);
    }
Simply returns toHex().hashCode();

@return toHex().hashCode()
crypto/hash/src/main/java/org/apache/shiro/crypto/hash/AbstractHash.java