public int compare(final byte[] buffer1, int offset1, int length1,
                           final byte[] buffer2, int offset2, int length2) {

            // short circuit equal case
            if (buffer1 == buffer2 &&
                    offset1 == offset2 &&
                    length1 == length2) {
                return 0;
            }

            // similar to Arrays.compare() but considers offset and length
            int end1 = offset1 + length1;
            int end2 = offset2 + length2;
            for (int i = offset1, j = offset2; i < end1 && j < end2; i++, j++) {
                int a = buffer1[i] & 0xff;
                int b = buffer2[j] & 0xff;
                if (a != b) {
                    return a - b;
                }
            }
            return length1 - length2;
        }
A byte array comparator based on lexicograpic ordering.
clients/src/main/java/org/apache/kafka/common/utils/Bytes.java