Case C-460/18 P: Judgment of the Court (First Chamber) of 19 December 2019 — HK v European Commission, Council of the European Union (Appeal — Civil service — Staff Regulations of Officials of the European Union — Article 1d — First paragraph of Article 17 of Annex VIII — Pension for the surviving spouse — Conditions for granting — Concept of ‘surviving spouse’ of a Union official — Marriage and non-marital partnership — Cohabitation — Principle of non-discrimination — Comparable situation — None — Condition of duration of marriage — Combating fraud — Justification)