private boolean isColumnQualifierChanged(ExtendedCell cell) {
    if (
      delColMap.isEmpty() && lastCqArray == null && cell.getQualifierLength() == 0
        && (PrivateCellUtil.isDeleteColumns(cell) || PrivateCellUtil.isDeleteColumnVersion(cell))
    ) {
      // for null columnQualifier
      return true;
    }
    return !PrivateCellUtil.matchingQualifier(cell, lastCqArray, lastCqOffset, lastCqLength);
  }
Reset the map if it is different with the last Cell. Save the cq array/offset/length for next
Cell.
@return If this put has duplicate ts with last cell, return the mvcc of last cell. Else return
        MAX_VALUE.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/querymatcher/NewVersionBehaviorTracker.java