(2) The term "collective bargaining" or "bargaining" means the performance of the mutual obligation of the representatives of the employer and the exclusive bargaining representative to meet at reasonable times in light of the time limitations of the budget-making process, and to bargain in good faith in an effort to reach agreement with respect to the wages, hours, and terms and conditions of employment: PROVIDED, That prior law, practice or interpretation shall be neither restrictive, expansive, nor determinative with respect to the scope of bargaining. A written contract incorporating any agreements reached shall be executed if requested by either party. The obligation to bargain does not compel either party to agree to a proposal or to make a concession. In the event of a dispute between an employer and an exclusive bargaining representative over the matters that are terms and conditions of employment, the commission shall decide which item(s) are mandatory subjects for bargaining and which item(s) are nonmandatory.