Neb. Rev. Stat. § 58-519

In any suit, action, or proceedings involving the validity or enforceability of any bond of a contracting public body or the security therefor brought after the lapse of thirty days after the bonds are issued, any such bond reciting in substance that it has been issued by the contracting public body to aid in financing a redevelopment project shall be conclusively deemed to have been issued for such purpose and such project shall be conclusively deemed to have been planned, located, and carried out in accordance with the purposes and provisions of the Nebraska Redevelopment Act.