Case C-670/18: Judgment of the Court (Eighth Chamber) of 2 April 2020 (request for a preliminary ruling from the Tribunale Amministrativo Regionale per la Sardegna — Italy) — CO v Comune di Gesturi (Reference for a preliminary ruling — Social policy — Principle of equal treatment in employment and occupation — Directive 2000/78/EC — Prohibition of all discrimination on grounds of age — Public call for expressions of interest — Conditions of participation — Exclusion of retired public-sector and private-sector employees)