Sovereign immunity — Property of foreign States — Lease of premises for embassy use — Action for rent arrears and repair costs — Judgment in default — Whether foreign State entitled to immunity from execution — Requirement to consider immunity from execution as a separate question where no entitlement to jurisdictional immunity — Rules of customary international law — Manner in which established — Whether rule of customary international law exists completely debarring measures of execution against a foreign State — Judgment relating to acts iure gestionis of foreign State — Whether execution against assets of a foreign State serving sovereign purposes admissible — Whether execution against assets of foreign State sewing the official functions of a diplomatic mission admissible — Whether classification of assets to be made according to municipal or international law — Application of test of whether or not the ability of the mission to function would be impaired — Whether general current bank account of foreign State used to cover embassy expenditure is immune from execution — Whether sending State can be required to provide details of the purposes of funds in such an account — Protection of individuals against the immunity of an embassy account being used as shield for private financial transactions — Whether the financial position of sending State consequent upon any attachment is relevant — The law of the Federal Republic of Germany