The state does hereby pledge to and agree with the holders of any general obligations issued under sections 7-560 to 7-579, inclusive, and with those parties who may enter into contracts with a municipality pursuant to the provisions of sections 7-560 to 7-579, inclusive, that the state will not limit or alter the rights hereby vested in a municipality until such obligations, together with the interest thereon, are fully met and discharged and such contracts are fully performed on the part of the municipality, provided nothing in sections 7-560 to 7-579, inclusive, shall preclude limitation or alteration if and when adequate provision shall be made by law for the protection of the holders of such general obligations of a municipality or those entering into such contracts with a municipality. A municipality as agent for the state is authorized to include this pledge and undertaking by the state in such general obligations.