Judgment of the Court (First Chamber) of 8 May 2019.#Ministero dell'Istruzione, dell'Università e della Ricerca - MIUR v Fabio Rossato and Conservatorio di Musica F.A. Bonporti.#Request for a preliminary ruling from the Corte di Appello di Trento.#Reference for a preliminary ruling — Social policy — Fixed-term work — Contracts concluded with a public sector employer — Measures to penalise misuse of fixed-term employment contracts — Conversion of the employment relationship into a relationship of indefinite duration — Limitation on the retroactive effect of the conversion