@Override
  public void configure(TestElement element) {
    super.configure(element);
    if (!(element instanceof StockParam)) return;
    StockParam sampler = (StockParam) element;

    configureHeaders(sampler);
  }
  @Override
  public void modifyTestElement(TestElement te) {
    StockParam sampler = (StockParam) te;
    sampler.clear();
    configureTestElement(sampler);

    super.modifyTestElement(sampler);

    sampler.setHeaders((Arguments) headers.createTestElement());
  }
 @Override
 public void clearGui() {
   super.clearGui();
   headers.clearGui();
 }
 @Override
 protected final void init() {
   super.init();
   mainPanel.add(headers);
 }