Cir. 1987))). While.challenges to specific terms do not always result in § 363(m) mootness, “those challenges that would claw back the sale' from a good-faith purchaser” will end in a finding of mootness. In re ICL Holding Co., 802 F.3d at 554. The “validity of the sale” inquiry gives effect to § 363(m)’s “clear preference in favor of upholding the validity of bankruptcy sales without unduly restricting the appellant’s right to contest errors of law made by the bankruptcy court.” In re Brown, 851 F.3d 619, 623 (6th Cir. 2017). It preserves appellate rights only in those rare circumstances where collateral issues not implicating a central or integral element of a sale are challenged. Cf. George W. Kuney, Slipping Into Mootness, Norton Ann. Surv. of Bankr, L. Part I, § 3 (West 2007) (<HOLDING>). In short, the validity prong of our test
recognizing that it is an unusual challenge to a sale that does not distort the validity of the sale and that the exception likely has meaning only when collateral issues are challenged holding that where property subject to the irss timely filed lien is sold during a nonjudicial sale and the irs is not given notice of the sale the sale of the property is made subject to and without disturbing the lien holding that the burden is on the defendant when the validity of the warrant is challenged holding in the analogous context of choiceoflaw in relation to the sale of personal property that compensation for arranging the sale is assessed apart from underlying sale holding that an assignment or sale of rights in the invention and potential patent rights is not a sale of the invention within the meaning of section 102b