Nationality — Acquisition and loss of — Acquisition of nationality of State of Israel by Italian citizen — Acquisition automatic upon immigration into Israel in absence of contrary declaration — Loss of Italian nationality upon “spontaneous” acquisition of foreign nationality — Whether acquisition of nationality of Israel by failure to make contrary declaration “spontaneous” within meaning of Italian law — Distinction between “spontaneous” and “voluntary” acquisition of foreign nationality — “Law of Return” of Israel, 1950 — Italian Nationality Law, 1912.