private static Insets parseInsets( String value )
		throws IllegalArgumentException
	{
		List<String> numbers = StringUtils.split( value, ',', true, false );
		try {
			return new InsetsUIResource(
				Integer.parseInt( numbers.get( 0 ) ),
				Integer.parseInt( numbers.get( 1 ) ),
				Integer.parseInt( numbers.get( 2 ) ),
				Integer.parseInt( numbers.get( 3 ) ) );
		} catch( NumberFormatException | IndexOutOfBoundsException ex ) {
			throw new IllegalArgumentException( "invalid insets '" + value + "'" );
		}
	}
Similar to Class.getSimpleName(), but includes enclosing class for nested classes.
flatlaf-core/src/main/java/com/formdev/flatlaf/UIDefaultsLoader.java