Wl-3353 Don’t NPE when bean hasn’t run init()

When you add a participant for the second time RSF seems to wrongly re-use a object from a previous request. This was causing a NPE. Fixing RSF is hard and so this is just a quick hack.
Merge pull request #16 from ox-it/WL-3352

Wl-3353 Don’t NPE when bean hasn’t run init()