Case C-385/18: Judgment of the Court (Second Chamber) of 19 December 2019 (request for a preliminary ruling from the Consiglio di Stato — Italy) — Arriva Italia Srl, Ferrotramviaria SpA, Consorzio Trasporti Aziende Pugliesi (CO.TRA.P) v Ministero delle Infrastrutture e dei Trasporti (Reference for a preliminary ruling — State aid — Notion — Public railway undertaking in difficulties — Aid measures — Allocation of financial aid — Aim — Continued operation of the public railway undertaking — Allocation to and shareholding in the capital of that public undertaking — Transfer to the capital of another public undertaking — Private investor test — Prior notification obligation for new aid)