public static long hash64(long data) {
        long hash = DEFAULT_SEED;
        long k = Long.reverseBytes(data);
        int length = Long.BYTES;
        // mix functions
        k *= C1;
        k = Long.rotateLeft(k, R1);
        k *= C2;
        hash ^= k;
        hash = Long.rotateLeft(hash, R2) * M + N1;
        // finalization
        hash ^= length;
        hash = fmix64(hash);
        return hash;
    }
Murmur3 64-bit variant. This is essentially MSB 8 bytes of Murmur3 128-bit variant.

@param data - input byte array
@return - hashcode
streams/src/main/java/org/apache/kafka/streams/state/internals/Murmur3.java