Tenn. Code Ann. § 9-21-902

A determination by the governing body that any refunding is advantageous or necessary to the local government, or that any of the amounts provided in § 9-21-904 should be included in such refunding, or that any of the outstanding obligations should be called for redemption on the first or any subsequent available redemption date or permitted to remain outstanding until their respective dates of maturity, shall be conclusive. However, the determination as to whether the general obligation refunding bonds can be sold at a private negotiated sale is subject to § 9-21-910(c).