// Shallow copy
	c := *j

	// Marshal metadata
	crc := hashDeterministicBytes(c.MetaSys)
	c.MetaSys = nil
	if bts, err := c.MarshalMsg(metaDataPoolGet()); err == nil {
		crc ^= xxhash.Sum64(bts)
		metaDataPoolPut(bts)
	}

	// Combine upper and lower part
	var tmp [4]byte
	binary.LittleEndian.PutUint32(tmp[:], uint32(crc^(crc>>32)))
	return tmp
}