XSLF - remove table column

import java.awt.geom.Rectangle2D;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

import org.apache.poi.xslf.usermodel.XMLSlideShow;
import org.apache.poi.xslf.usermodel.XSLFSlide;
import org.apache.poi.xslf.usermodel.XSLFTable;
import org.apache.poi.xslf.usermodel.XSLFTableCell;
import org.apache.poi.xslf.usermodel.XSLFTableRow;
import org.openxmlformats.schemas.drawingml.x2006.main.CTTableCell;

public class XslfRemoveTableColumn {
    public static void main(String args[]) throws IOException {
        // prepare sample table/slide with merged cells
        XMLSlideShow ppt = new XMLSlideShow();
        XSLFSlide sl = ppt.createSlide();
        XSLFTable tab = sl.createTable();
        initRow(tab, "111111");
        initRow(tab, "122122");
        initRow(tab, "112222");
        initRow(tab, "133322");
        initRow(tab, "333122");
        tab.setAnchor(new Rectangle2D.Double(100, 100, 200, 200));

        try (FileOutputStream fos = new FileOutputStream("bla.pptx")) {
            ppt.write(fos);
        }
        ppt.close();

        try (FileInputStream fis = new FileInputStream("bla.pptx")) {
            ppt = new XMLSlideShow(fis);
        }

        tab = (XSLFTable)ppt.getSlides().get(0).getShapes().get(0);

        // actually remove the column
        removeColumn(tab, 3);

        try (FileOutputStream fos = new FileOutputStream("bla2.pptx")) {
            ppt.write(fos);
        }
        ppt.close();
    }

    private static void removeColumn(XSLFTable table, int col) {
nextRow:for (final XSLFTableRow row : table) {
            Iterator<XSLFTableCell> it = row.iterator();
            int gridSpan;
            for (int idx=0, idxXml=0; it.hasNext(); idx+=gridSpan, idxXml++) {
                final XSLFTableCell c = it.next();
                gridSpan = c.getGridSpan();
                if (idx <= col && col < idx+gridSpan) {
                    if (gridSpan > 1) {
                        ((CTTableCell)c.getXmlObject()).setGridSpan(gridSpan-1);
                        // check for merged cells
                        for (; it.hasNext() && idx<col; idx++, idxXml++) {
                            final XSLFTableCell mergedC = it.next();
                            if (!mergedC.isMerged()) {
                                continue nextRow;
                            }
                        }
                    }
                    row.getXmlObject().removeTc(idxXml);
                    it.remove();
                    break;
                }
            }
        }
        table.getCTTable().getTblGrid().removeGridCol(col);
    }

    private static List<XSLFTableCell> initRow(XSLFTable table, String iv) {
        XSLFTableRow row = table.addRow();
        for (int idx=0; idx<iv.length(); idx++) {
            XSLFTableCell c = row.addCell();
            c.setText(""+idx);
            int span = iv.charAt(idx)-'0';
            if (span > 1) {
                ((CTTableCell)c.getXmlObject()).setGridSpan(span);
            }
            for (int spanIdx=0; spanIdx<span-1; spanIdx++, idx++) {
                c = row.addCell();
                ((CTTableCell)c.getXmlObject()).setHMerge(true);
            }
        }
        return row.getCells();
    }
}