Case T-18/19: Judgment of the General Court of 5 October 2020 — Brown v Commission (Civil service — Officials — Official with United Kingdom nationality at the date of entering the service — Withdrawal of the United Kingdom from the European Union — Acquisition of the nationality of the country of employment during the course of a career — Loss of the expatriation allowance — Equal treatment — Principle of non-discrimination — Article 4(1) of Annex VII to the Staff Regulations)