Case C-18/19: Judgment of the Court (First Chamber) of 2 July 2020 (request for a preliminary ruling from the Bundesgerichtshof — Germany) — WM v Stadt Frankfurt am Main (Reference for a preliminary ruling — Area of freedom, security and justice — Directive 2008/115/EC — Common standards and procedures in Member States for returning illegally staying third-country nationals — Conditions of detention — Article 16(1) — Detention in prison accommodation for the purpose of removal — Third-country national who poses a serious threat to public policy or public security)