Case C-453/14: Judgment of the Court (Fourth Chamber) of 21 January 2016 (request for a preliminary ruling from the Verwaltungsgerichtshof — Austria) — Vorarlberger Gebietskrankenkasse, Alfred Knauer v Landeshauptmann von Vorarlberg (Reference for a preliminary ruling — Regulation (EC) No 883/2004 — Article 5 — Meaning of ‘equivalent benefits’ — Equal treatment of old-age benefits of two Member States of the European Economic Area — National legislation taking into account old-age benefits received in other Member States for the purpose of calculating social security contributions)