The State of Nebraska does hereby pledge to and agree with the holders of any obligations issued under the Nebraska Elementary and Secondary School Finance Authority Act and with those parties who may enter into contracts with the authority pursuant to the act that the state will not limit or alter the rights vested in the authority until such obligations, together with the interest thereon, are fully met and discharged and such contracts are fully performed on the part of the authority, except that nothing contained in this section shall preclude such limitation or alteration if and when adequate provision is made by law for the protection of the holders of such obligations of the authority or those entering into such contracts with the authority.