2. Users and data holders may contractually restrict or prohibit accessing, using or further sharing data, if such processing could undermine security requirements of the connected product, as laid down by Union or national law, resulting in a serious adverse effect on the health, safety or security of natural persons. Sectoral authorities may provide users and data holders with technical expertise in that context. Where the data holder refuses to share data pursuant to this Article, it shall notify the competent authority designated pursuant to Article 37.