If any of the commissioners or officers of an authority whose signatures appear on any bonds or coupons cease to be a commissioner or officer before the delivery of the bonds, the signatures are valid and sufficient for all purposes the same as if the commissioner or officer had remained in office until the delivery had been completed. Any bonds issued under this chapter must be fully negotiable. In an action, suit, or proceeding involving the validity or enforceability of any bond of an authority or of the security for the bond, the bond must be deemed conclusively to have been issued for a housing project if the bond recites that it has been issued by the authority to aid in financing a housing project to provide dwelling accommodations for persons of low or moderate income. The project is planned, located, and constructed in accordance with this chapter if this statement is contained in the bond.