Sovereign immunity — Foreign States and State-owned corporations — National Iranian Oil Company — Contracts for construction of pipelines — Whether NIOC entitled to jurisdictional immunity — Whether immunity available to undertakings of foreign States endowed with independent legal personality — Acts iure imperii and iure gestionis — Whether exploitation of oil reserves a sovereign activity — Relevance of United Nations Resolutions on OPEC — Whether oil pipeline construction a sovereign activity — The law of the Federal Republic of Germany