Case C-579/17: Judgment of the Court (Second Chamber) of 28 February 2019 (request for a preliminary ruling from the Arbeits- und Sozialgericht Wien — Austria) — BUAK Bauarbeiter-Urlaubs- u. Abfertigungskasse v Gradbeništvo Korana d.o.o. (Reference for a preliminary ruling — Judicial cooperation in civil matters — Regulation (EU) No 1215/2012 — Article 1(1) — Scope — Civil and commercial matters — Article 1(2) — Matters excluded — Social security — Article 53 — Application for the issue of the certificate certifying that the judgment delivered by the court of origin is enforceable — Judgment relating to a claim for wage supplements regarding annual leave pay that a social security body has against an employer with respect to the posting of workers — Exercise of a judicial function by the court ruling in the case)