The "message.getData()" is NOT valid for SimplePush variants, but for all other variants.

This block:
https://github.com/aerogear/aerogear-unifiedpush-server/blob/master/push/src/main/java/org/jboss/aerogear/unifiedpush/message/SenderServiceImpl.java#L100-L124

needs to be updated to differenciate between SimplePush and other variants.