addNonNull(v);
addNonNull(v, JScrollPane.VERTICAL_SCROLLBAR);
  public void setVerticalScrollBar(JScrollBar v)  {    if (verticalScrollBar == v)      return;        JScrollBar old = verticalScrollBar;    removeNonNull(old);    verticalScrollBar = v;    addNonNull(v);    firePropertyChange("verticalScrollBar", old, v);    sync();    if (old != null)      {        BoundedRangeModel model = old.getModel();        if (model != null)          model.removeChangeListener(scrollListener);      }    if (v != null)      {        BoundedRangeModel model = v.getModel();        if (model != null)          model.addChangeListener(scrollListener);      }  }