36According to that court, such a solution may find support, on the one hand, in the lessons drawn from the judgment of 11 March 2015, Oberto and O’Leary (C‑464/13 and C‑465/13, ‘the judgment in Oberto and O’Leary’, EU:C:2015:163), in which the Court already accepted, relying on the rules of the Vienna Convention, that the Complaints Board had been entitled to confer on itself sole jurisdiction to hear and determine appeals against an act of the Headteacher of a European School that adversely affected a teacher at that school.