When systems grow they must be modularized to keep control. Whereas that sounds not really fancy, it leads to additional aspects to be considered by a configuration system.

The default configuration hereby should always be present, whereas additional configurations are optional. Users want to be able to check the availability of such an additional configuration.

Of course, additional configuration must be identifiable. The best way to do is to be discussed, nevertheless the mechanism must not depend on Java EE and the identifying keys must be serializable easily. Basically simple names are sufficient and woukld provide exact this required functionality.