Case C-575/18 P: Judgment of the Court (Grand Chamber) of 9 July 2020 — Czech Republic v European Commission (Appeal — Own resources of the European Union — Financial liability of the Member States — Request to be released from the obligation to make own resources available — Action for annulment — Admissibility — Letter from the European Commission — Concept of ‘actionable measure’ — Article 47 of the Charter of Fundamental Rights of the European Union — Effective judicial protection — Action alleging unjust enrichment on the part of the European Union)