Sovereign immunity — Foreign States — Enforcement of arbitral award against foreign State — Proceedings for obtaining an exequatur — Whether foreign State entitled to jurisdictional immunity — Whether any requirement under international law of connection between acts in question and the forum — Acts iure imperii and iure gestionis — Whether any rule of international law completely debarring measures of execution against a foreign State — Whether proceedings to obtain an exequatur for award violate a foreign State's immunity from execution — Convention on the Recognition and Enforcement of Foreign Arbitral Awards, 1958 — Applicability to awards to which non-signatories are party — Whether only applicable to awards which are arbitral awards according to the law of a specific State