"Make object access work with ObjectStorage" removed access to properties of ObectStorages
Unfortunately with https://review.typo3.org/29923 the access to properties which are not numeric, broke.
Have a look at this gist, please: https://gist.github.com/alexanderschnitzler/ad4b4f16f91781882853
One can say, that it's not good practice to extend an ObjectStorage with own properties but I saw that a lot in the wild, e.g. for building simple tree-like structures.