The provisions of article XI-A of the State Finance Law and of these rules shall apply to all proper invoices received by the State on or after July 1, 1984, including invoices submitted under written contracts entered into on or prior to July 1, 1984 which contain inconsistent interest provisions, except where the interest provisions of such contract entered into on or prior to July 1, 1984 will provide a greater interest payment to the contractor, in which case the provisions of the contract shall govern. No contract entered into after July 1, 1984 shall contain any provision requiring the payment of interest in a manner inconsistent with article XI-A of the State Finance Law or these rules, including any provision requiring the payment of a greater amount of interest, and any such provision included in a contract shall be null and void.