OSIS-2790 parent can be null prevent bug on dirty data
OSIS-2790 parent can be null prevent bug on dirty data

uclouvain/osis,uclouvain/osis,uclouvain/osis,uclouvain/OSIS-Louvain,uclouvain/OSIS-Louvain,uclouvain/osis,uclouvain/OSIS-Louvain