Judgment of the Court (First Chamber) of 21 March 2019.#Unareti SpA v Ministero dello Sviluppo Economico and Others.#Request for a preliminary ruling from the Consiglio di Stato.#Reference for a preliminary ruling — Internal market in natural gas –Public service distribution concessions — Early termination of concessions at the end of a transitional period — Reimbursement by the incoming concessionaire to the outgoing concessionaire — Principle of legal certainty.#Case C-702/17.