An indenture may include a clause relating to the bonds issued pursuant to the indenture which limits, restricts, or prohibits any right, power, or privilege of the regents to mortgage or otherwise encumber, sell, lease, or dispose of any improvements constructed from the proceeds of the bonds, or to enter into any lease or agreement which impairs or impedes the operation of a project, or any part of a project, necessary to secure adequate revenues or which otherwise impairs or impedes the rights of the holders of the bonds with respect to such revenues.