Steps to reproduce:
1. Install the latest version of https://bitbucket.org/opencast-community/opencast-contrib-wowza-adaptive-streaming (currently in review, because of this issue, January 12th 2017)
2. Upload a video
It will fail in distribution with an NPE. This happens because the new "tracks" with the adaptive streaming files do not have a representation in the current mediapackage and loading them with their ID fails, as they don't have an ID yet. The loading step for these files need to be skipped.