private ExtendedCell getHighest(ExtendedCell first, ExtendedCell second) {
    if (first == null && second == null) {
      return null;
    }
    if (first != null && second != null) {
      int compare = segment.compare(first, second);
      return (compare > 0 ? first : second);
    }
    return (first != null ? first : second);
  }
Private internal method that returns the higher of the two key values, or null if they are both
null
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/SegmentScanner.java