Case T-696/17: Judgment of the General Court of 20 September 2019 — Havenbedrijf Antwerpen and Maatschappij van de Brugse Zeehaven v Commission (State aid — Corporate tax exemption scheme implemented by Belgium in favour of its ports — Decision declaring the aid scheme incompatible with the internal market — Concept of economic activity — Services of general economic interest — Non-economic activities — Separable nature — Selective nature — Request for a transitional period)