static int getButtonType( Component c ) {
		if( !(c instanceof AbstractButton) )
			return TYPE_OTHER;

		String value = getButtonTypeStr( (AbstractButton) c );
		if( value == null )
			return TYPE_OTHER;

		switch( value ) {
			case BUTTON_TYPE_SQUARE:		return TYPE_SQUARE;
			case BUTTON_TYPE_ROUND_RECT:	return TYPE_ROUND_RECT;
			default:						return TYPE_OTHER;
		}
	}
Returns true if the button has an icon but no text,
or it does not have an icon and the text is either "..." or one character.
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java