Case T-209/15: Judgment of the General Court of 21 December 2021 — Gmina Kosakowo v Commission (State aid — Airport infrastructure — Public funding by the municipalities of Gdynia and Kosakowo for setting up the Gdynia-Kosakowo Airport — Decision declaring the aid incompatible with the internal market and ordering its recovery — Advantage — Market economy operator principle — Effect on trade between Member States — Adverse effect on competition — Recovery — Obligation to state reasons)