Glad to say that, after a long period of inactivity, the project development has resumed. New developpers are welcome since I'm still alone ...
RconX dependencies may change. I've just discovered Steam-condenser Java library which seems to be more accurate, easier to manage servers and provides more features.
For the moment, the application is still under design.
The project is still under planning. Development will soon begin, as soon as the design will be done.