Exception in thread "main" java.lang.ExceptionInInitializerError

[Ingo]

I'm getting the following error when trying to run the ChatServer example.

Exception in thread "main" java.lang.ExceptionInInitializerError
    at com.yongboy.socketio.MainServer.<init>(MainServer.java:21)
    at chatserver.ChatServer.main(ChatServer.java:45)
Caused by: java.util.MissingResourceException: Can't find bundle for base name socketio, locale de_DE
    at java.util.ResourceBundle.throwMissingResourceException(ResourceBundle.java:1499)
    at java.util.ResourceBundle.getBundleImpl(ResourceBundle.java:1322)
    at java.util.ResourceBundle.getBundle(ResourceBundle.java:724)
    at com.yongboy.socketio.server.SocketIOManager$Option.<init>(SocketIOManager.java:48)
    at com.yongboy.socketio.server.SocketIOManager.<clinit>(SocketIOManager.java:25)
    ... 2 more
Java Result: 1

Why is this and more importantly, how can I fix this?

Thanks