@Override
  public int compareTo(Bytes that) {
    return BYTES_RAWCOMPARATOR.compare(this.bytes, this.offset, this.length, that.bytes,
      that.offset, that.length);
  }
Define the sort order of the Bytes.
@param that The other bytes writable
@return Positive if left is bigger than right, 0 if they are equal, and negative if left is
        smaller than right.
hbase-common/src/main/java/org/apache/hadoop/hbase/util/Bytes.java