Mich. Comp. Laws § 15.326

Sec. 6. If any public entity has, prior to the effective date of this act, entered into any contract under which moneys, goods, materials, labor or services have been actually received by the public entity, which was void or voidable under any act, charter or rule of law because of a conflict of interest on the part of a public servant at the time of the execution thereof, such contract shall be fully enforceable notwithstanding such conflict of interest, by any party thereto other than such public servant.