Case C-452/17: Judgment of the Court (Fourth Chamber) of 21 November 2018 (request for a preliminary ruling from the Tribunal de commerce de Liège — Belgium) — Zako SPRL v Sanidel SA (Reference for a preliminary ruling — Self-employed commercial agents — Directive 86/653/EEC — Article 1(2) — Definition of ‘commercial agent’ — Self-employed intermediary performing his activities from the principal’s business premises — Performance of tasks other than those related to the negotiation of sales or the purchase of goods for the principal)