Case C-523/18: Judgment of the Court (Fifth Chamber) of 19 December 2019 (request for a preliminary ruling from the Audiencia Nacional — Spain) — Engie Cartagena SL v Ministerio para la Transición Ecológica, formerly Ministerio de Industria, Energía y Turismo (Reference for a preliminary ruling — Internal market in electricity — Common rules — Directive 2003/54/EC — Article 3(2) — Directive 2009/72/EC — Article 3(2) — Public service obligations — Meaning — National rules — Financing of energy efficiency plans — Designation of electricity generating undertakings — Mandatory contribution)