Program: 71015
Project: 71015
Buggy source:
private void synchronize(){
  XlsContainer rowContainer=getCurrentContainer();
  ContainerSizeInfo rowSizeInfo=rowContainer.getSizeInfo();
  int startCoordinate=rowSizeInfo.getStartCoordinate();
  int endCoordinate=rowSizeInfo.getEndCoordinate();
  int startColumnIndex=axis.getColumnIndexByCoordinate(startCoordinate);
  int endColumnIndex=axis.getColumnIndexByCoordinate(endCoordinate);
  int maxRowIndex=0;
  int rowIndexes[]=new int[endColumnIndex - startColumnIndex];
  for (int currentColumnIndex=startColumnIndex; currentColumnIndex < endColumnIndex; currentColumnIndex++) {
    int rowIndex=cache.getMaxRowIndex(currentColumnIndex);
    rowIndexes[currentColumnIndex - startColumnIndex]=rowIndex;
    maxRowIndex=maxRowIndex > rowIndex ? maxRowIndex : rowIndex;
  }
  rowContainer.setRowIndex(maxRowIndex);
  for (int currentColumnIndex=startColumnIndex; currentColumnIndex < endColumnIndex; currentColumnIndex++) {
    int rowspan=maxRowIndex - rowIndexes[currentColumnIndex - startColumnIndex];
    if (rowspan > 0) {
      SheetData data=null;
      SheetData upstair=cache.getColumnLastData(currentColumnIndex);
      if (upstair != null && canSpan(upstair,rowContainer)) {
        SheetData predata=upstair;
        int rs=predata.getRowSpan() + rowspan;
        predata.setRowSpan(rs);
        BlankData blankData=new BlankData(getRealData(predata));
        if (!isInContainer(predata,rowContainer)) {
          blankData.decreasRowSpanInDesign();
        }
        data=blankData;
        for (int p=0; p < rowspan; p++) {
          cache.addData(currentColumnIndex,data);
        }
      }
    }
  }
}

Fixed version (ground truth):
private void synchronize(){
  XlsContainer rowContainer=getCurrentContainer();
  ContainerSizeInfo rowSizeInfo=rowContainer.getSizeInfo();
  int startCoordinate=rowSizeInfo.getStartCoordinate();
  int endCoordinate=rowSizeInfo.getEndCoordinate();
  int startColumnIndex=axis.getColumnIndexByCoordinate(startCoordinate);
  int endColumnIndex=axis.getColumnIndexByCoordinate(endCoordinate);
  int maxRowIndex=0;
  int rowIndexes[]=new int[endColumnIndex - startColumnIndex];
  for (int currentColumnIndex=startColumnIndex; currentColumnIndex < endColumnIndex; currentColumnIndex++) {
    int rowIndex=cache.getMaxRowIndex(currentColumnIndex);
    rowIndexes[currentColumnIndex - startColumnIndex]=rowIndex;
    maxRowIndex=maxRowIndex > rowIndex ? maxRowIndex : rowIndex;
  }
  rowContainer.setRowIndex(maxRowIndex);
  for (int currentColumnIndex=startColumnIndex; currentColumnIndex < endColumnIndex; currentColumnIndex++) {
    int rowspan=maxRowIndex - rowIndexes[currentColumnIndex - startColumnIndex];
    if (rowspan > 0) {
      SheetData upstair=cache.getColumnLastData(currentColumnIndex);
      if (upstair != null && canSpan(upstair,rowContainer)) {
        SheetData predata=upstair;
        int rs=predata.getRowSpan() + rowspan;
        predata.setRowSpan(rs);
        SheetData realData=getRealData(predata);
        BlankData blankData=new BlankData(realData);
        if (!isInContainer(predata,rowContainer)) {
          blankData.decreasRowSpanInDesign();
        }
        int rowIndex=predata.getRowIndex();
        for (int p=1; p <= rowspan; p++) {
          BlankData blank=new BlankData(predata);
          blank.setRowIndex(rowIndex + p);
          cache.addData(currentColumnIndex,blank);
        }
      }
    }
  }
}