Belligerent Occupation — Legislative Functions of Occupant — Legislation Affecting Private Property — Whether Lawful — Article 43 of Hague Regulations of 1907 — Invasion and Occupation in Contravention of General Treaty for Renunciation of War, 1928 — Whether State Committing Such Invasion Entitled to Rights of a Belligerent Occupant — Law in Force in Territory Thus Invaded — Contracts of Sale of Immovable Property During Occupation — Impossibility of Compliance with Requirement of Form of Notarial Act — Validity of Such Contracts