Tenn. Code Ann. § 6-51-123

Notwithstanding Chapter 707 of the Public Acts of 2014, this part, or any other law to the contrary, any county having a metropolitan form of government may expand the area of its urban services district using any method authorized by its charter. Such expansion may also be accomplished using any method, identified by charter reference to general annexation law, that was applicable at the time the charter or amendment was approved by referendum held pursuant to Article XI, § 9 of the Tennessee Constitution and § 7-2-106(c) or § 7-2-108(a)(20).