How to split a row whose rowspan > 1 evenly

[ObsisMc]

I use following code to get the result like the first image.

PdfPTable table = new PdfPTable(2);
PdfPCell cell = new PdfPCell();
cell.setRowspan(2);
cell.addElement(new Chunk("rowspanrowspanrowspanrowspanrowspanrowspanrowspanrowspanrowspanrowspanrowspanrowspanrowspanrowspanrowspan"));
table.addCell(cell);

table.addCell("row1"); 
table.addCell("row2");
document.add(table);

However, I want heights of rows in the second column to be the same like following image.

How should I change my code to get the expected result.

[ObsisMc]

After my investigations, I find that maybe the first case is a default result. Do you think that letting it be split evenly is reasonable?

[asturio]

It seems a nice feature.