Specialized BytesRef comparator that StringSorter has optimizations for.
Return the unsigned byte to use for comparison at index i, or -1 if all bytes that are useful for comparisons are exhausted. This may only be called with a value of i between 0 included and comparedBytesCount excluded.
i
-1
0
comparedBytesCount
Compare two bytes refs that first k bytes are already guaranteed to be equal.