code: public void addElement(Element element) throws DocumentException {
          if (simple) {
              columnText.addElement(element);
          } else if (element instanceof Phrase) {
              columnText.addText((Phrase) element);
          } else if (element instanceof Chunk) {
              columnText.addText((Chunk) element);
          } else {
              throw new DocumentException("Can't add " + element.getClass() + " to MultiColumnText with complex columns");
          }
      }
docs: Add an element to be rendered in a column.
  Note that you can only add a <CODE>Phrase</CODE>
  or a <CODE>Chunk</CODE> if the columns are
  not all simple.  This is an underlying restriction in
  {@link com.lowagie.text.pdf.ColumnText}
  
  @param element element to add
  @throws DocumentException if element can't be added