Case C-666/20 P: Judgment of the Court (Seventh Chamber) of 24 March 2022 — Gesamtverband Verkehrsgewerbe Niedersachsen eV (GVN) v European Commission, Federal Republic of Germany, Land Niedersachsen (Germany) (Appeal — State aid — Concept of ‘aid’ — Public passenger transport — Compensating the costs related to the performance of public service obligations — Transfer of financial resources between public authorities — Obligation for the municipal transport authorities to determine reduced tariffs for students and apprentices — No advantage granted by the State to an undertaking — Concept of ‘undertaking’)