public 
	String setProperty(String name, String value) {
		String oldValue = getProperty(name);
		if (value == null)
			return (String) properties.remove(name);
		else if (oldValue == null)
			return (String) properties.setProperty(name, value);
		else if (value.isEmpty() && !oldValue.isEmpty())
			return null;
		else return (String) properties.setProperty(name, value);
		
	}