Case C-29/19: Judgment of the Court (Eighth Chamber) of 23 January 2020 (request for a preliminary ruling from the Bundessozialgericht — Germany) — ZP v Bundesagentur für Arbeit (Reference for a preliminary ruling — Social security — Migrant workers — Regulation (EC) No 883/2004 — Unemployment benefits — Calculation — Failure to take account of the final salary received in the Member State of residence — Reference period not of sufficient duration — Salary received following the employment relationship coming to an end — Person having previously been active as an employed person in Switzerland)