public @Nullable Icon getIcon(boolean expanded) {
      // thanks to invokeLater() in TreeUtil.showAndSelect(), we can get calls to getIcon() after the tree has been disposed
      final NamedConfigurable configurable = getConfigurable();
      if (configurable != null) {
        return configurable.getIcon(expanded);
      }
      return null;
    }
public @Nullable Icon getIcon(boolean expanded)