Case C-342/19 P: Judgment of the Court (First Chamber) of 17 December 2020 — Fabio De Masi, Yanis Varoufakis v European Central Bank (Appeal — Access to European Central Bank (ECB) documents — Decision 2004/258/EC — Article 4(3) — Exceptions — Document received by the ECB — Opinion from an external service provider — Internal use as part of deliberations and preliminary consultations — Refusal to grant access)