Commentary for Bava Batra 42:1

Note 516: And [in a case of] an alleyway that is a dead end from three sides and Reuven lives next to the dead end; and Shimon comes to live next to the open end, such that the [gentile who has a business arrangement with Reuven] would not be able to walk [to Reuven] if he did not first walk in front of Shimon's entrance - it appears that [Reuven] can prevent him [from opening a competing business there], like the [statement] of Rav Huna. See the chapter [entitled] Chezkat HaBatim regarding the property of [gentiles], etc.; and also the chapter [entitled] HaOmer regarding [the case of] Rav Gidel who was turning over, etc.; and the first chapter of Bava Metzia regarding one who lifted a lost object [to acquire it] for his fellow. Aviasaf.