private boolean isStillAtSeekTargetAfterSkippingNewerKvs(Cell seekKey) throws IOException {
    setCurrentCell(hfs.getCell());
    return skipKvsNewerThanReadpointReversed() && getComparator().compareRows(cur, seekKey) <= 0;
  }
Seeks before the seek target cell and saves the location to {@link #previousRow}. If there
doesn't exist a KV in this file before the seek target cell, reposition the scanner at the
beginning of the storefile (in preparation to a reseek at or after the seek key) and set the
{@link #previousRow} to null. If {@link #previousRow} is ever non-null and then transitions to
being null again via this method, that's because there doesn't exist a row before the seek
target in the storefile (i.e. we're at the beginning of the storefile)
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFileScanner.java