The Problem can be reproduced by doing following steps:
1. Step.:
Loading a Properties File via ResourceBundle rb = ResourceBundle.getBundle("file.properties");
2. Step.:
Changing/Adding values to the properties file and saving it.
3. Step.: Accessing/Reading the properties file again.
Step 3 is not trivial as ResourceBundle keeps the properties file cached. Therefore you can't access the new values of the properties file. Though there is a function "rb.clearCache()" which should do excatly what I want it does not! work.
Therefore a workaround is needed.