Case C-427/18 P: Judgment of the Court (Tenth Chamber) of 26 February 2020 — European External Action Service v Ruben Alba Aguilera and Others (Appeal — Civil service — Officials and members of staff — European External Action Service (EEAS) — Remuneration — Staff Regulations — Article 110 — EU staff posted to a third country — Annex X — Third subparagraph of Article 1 and Article 10 — Allowance for living conditions — Annual revision and adjustment — Reduction for staff posted to Ethiopia — Requirement to adopt general implementing provisions beforehand — Scope)