Affordable Housing Fee Challenge. The Parties agree that if a Third_Party Challenge is initiated regarding the validity or enforceability of this Agreement or, specifically of the Affordable Housing Fee, Developer shall not sell [or lease?] the residential units designated for and required to complete the On-Site Requirements until the validity and enforceability of this Agreement, including payment of the Affordable Housing Fee, has been finally determined and upheld. If this Agreement or the Affordable Housing Fee is not upheld (on any final appeal), then Developer will satisfy the On-Site Requirements with the designated residential units.