docs: public void addCell(groovy.swing.impl.TableLayoutCell tag) {
          int gridx = 0;
          for (Iterator iter = cells.iterator(); iter.hasNext(); ) {
              groovy.swing.impl.TableLayoutCell cell = (groovy.swing.impl.TableLayoutCell) iter.next();
              gridx += cell.getColspan();
          }
          tag.getConstraints().gridx = gridx;
          cells.add(tag);
      }