Case C-102/15: Judgment of the Court (Second Chamber) of 28 July 2016 (request for a preliminary ruling from the Fővárosi Ítélőtábla — Hungary) — Gazdasági Versenyhivatal v Siemens Aktiengesellschaft Österreich (Reference for a preliminary ruling — Judicial cooperation in civil matters — Regulation (EC) No 44/2001 — Jurisdiction and the recognition and enforcement of judgments in civil and commercial matters — Scope ratione materiae — Recovery of sum not due — Unjust enrichment — Debt arising from the unjustified repayment of a fine for infringement of competition law)