New Post: Different behavior in ShiftRows with .xls and .xlsx in NPOI 2.3.0

There is a different behavior between shifting rows in .xls and .xlsx files. I have a snippet below which I use to copy rows. In 2.2.3, it was broken for .xlsx but a user told me here that it is fine now: http://stackoverflow.com/questions/41369004/npoi-poi-excel-lib-isheet-shiftrows-index-out-of-range-exception.

Here's my function:

public void CopyRow(IWorkbook iWorkbook, ISheet iSheet, int sourceRowNum, int destinationRowNum)
    {
        // Get the source / new row
        IRow newRow = iSheet.GetRow(destinationRowNum);
        IRow sourceRow = iSheet.GetRow(sourceRowNum);

        if (newRow == null)
        {
            iSheet.CreateRow(destinationRowNum);
            newRow = iSheet.GetRow(destinationRowNum);
        }

        if (newRow.RowNum != destinationRowNum)
        {
            destinationRowNum = newRow.RowNum;
        }

        // If the row exist in destination, push down all rows by 1 else create a new row
        if (newRow != null)
        {
            iSheet.ShiftRows(destinationRowNum, iSheet.LastRowNum, 1);
        }
        else
        {
            newRow = iSheet.CreateRow(destinationRowNum);
        }

        //newRow = iSheet.GetRow(destinationRowNum);

        // Loop through source columns to add to new row
        for (int i = 0; i < sourceRow.LastCellNum; i++)
        {
            // Grab a copy of the old/new cell
            ICell oldCell = sourceRow.GetCell(i);
            ICell newCell = newRow.CreateCell(i);

            // If the old cell is null jump to next cell
            if (oldCell == null)
            {
                newCell = null;
                continue;
            }

            // Copy style from old cell and apply to new cell
            //ICellStyle newCellStyle = iWorkbook.CreateCellStyle();
            //newCellStyle.CloneStyleFrom(oldCell.CellStyle);
            //;
            //newCell.CellStyle = newCellStyle;
            newCell.CellStyle = oldCell.CellStyle;

            // If there is a cell comment, copy
            if (oldCell.CellComment != null)
            {
                newCell.CellComment = oldCell.CellComment;
            }

            // If there is a cell hyperlink, copy
            if (oldCell.Hyperlink != null)
            {
                newCell.Hyperlink = oldCell.Hyperlink;
            }

            // Set the cell data type
            newCell.SetCellType(oldCell.CellType);

            // Set the cell data value
            switch (oldCell.CellType)
            {
                case CellType.Blank:
                    newCell.SetCellValue(oldCell.StringCellValue);
                    break;
                case CellType.Boolean:
                    newCell.SetCellValue(oldCell.BooleanCellValue);
                    break;
                case CellType.Error:
                    newCell.SetCellErrorValue(oldCell.ErrorCellValue);
                    break;
                case CellType.Formula:
                    newCell.SetCellFormula(oldCell.CellFormula);
                    break;
                case CellType.Numeric:
                    newCell.SetCellValue(oldCell.NumericCellValue);
                    break;
                case CellType.String:
                    newCell.SetCellValue(oldCell.RichStringCellValue);
                    break;
            }
        }

        // If there are are any merged regions in the source row, copy to new row
        for (int i = 0; i < iSheet.NumMergedRegions; i++)
        {
            CellRangeAddress cellRangeAddress = iSheet.GetMergedRegion(i);
            if (cellRangeAddress.FirstRow == sourceRow.RowNum)
            {
                CellRangeAddress newCellRangeAddress = new CellRangeAddress(newRow.RowNum,
                          (newRow.RowNum +
                                     (cellRangeAddress.LastRow - cellRangeAddress.FirstRow
                                                )),
                          cellRangeAddress.FirstColumn,
                          cellRangeAddress.LastColumn);
                iSheet.AddMergedRegion(newCellRangeAddress);
            }
        }
    }

If you step through it using an .xls file, it works as it did in NPOI 2.2.3. However, using an .xlsx file, the newRow.RowNum increases + 1 from the original destinationRowNum it was set to after calling ShiftRows, while with an .xls the newRow.RowNum stays the same. This ends up with null reference exceptions. Anyone have a workaround or know why they behave differently?