@NotNull
  private MultiRowFlowPanel addRowIfNecessary(@NotNull MultiRowFlowPanel panel) {
    if (panel.getComponentCount() <= 0) {
      return panel;
    }
    add(panel, new GridBag().anchor(GridBagConstraints.WEST).weightx(1).fillCellHorizontally().coverLine());
    myRows.add(panel);
    return new MultiRowFlowPanel(
      FlowLayout.LEFT, ArrangementConstants.HORIZONTAL_GAP, ArrangementConstants.VERTICAL_GAP
    );
  }
@NotNull
  private MultiRowFlowPanel addRowIfNecessary(@NotNull MultiRowFlowPanel panel)