Which project configuration you want to save ?
If you have workitemhandler, you can add the properties file in the same project classpath.
You can use the server's classpath as well but would be helpful if you can explain bit more.
For example, I have created a workitemhandler to push messages via WebSocket.
I would like configure socket server url into an external property file :
I don't want add properties in the project because properties aren't the same according to the environment (development, production,...).
I haven't tried this before, but in your workitemhandler you can read System Properties which will point to the properties file & you can read it from there, that can be the solution, though might not be best.