protected static ExtendedCell createStartKeyFromRow(byte[] startRow, ScanInfo scanInfo) {
    return PrivateCellUtil.createFirstDeleteFamilyCellOnRow(startRow, scanInfo.getFamily());
  }
Delegate to {@link Filter#getNextCellHint(Cell)}. If no filter, return {@code null}.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/querymatcher/ScanQueryMatcher.java