Bonds as payment for services.

Any district is authorized to enter into agreements for the delivery of any revenue bonds, general obligation bonds or assessment bonds at one time or from time to time as full or partial payment for the services of any engineer or work done by any contractor who may have been retained or hired or been awarded a contract for the construction of all or any part of a water system or sewer system; provided, however, that any such bonds so delivered for payment of such services or work performed shall have been authorized and issued in the manner provided in this law and shall otherwise conform to the provisions hereof.