private Color getDefaultBackground( JComponent c ) {
		Container parent = c.getParent();
		return (parent instanceof CellRendererPane && parent.getParent() != null)
			? parent.getParent().getBackground()
			: defaultBackground;
	}
Returns the default background color of the component.
If the component is used as cell renderer (e.g. in JTable),
then the background color of the renderer container is returned.
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatRadioButtonUI.java