(a) Any executed contract for the purchase of goods or services by a state or local agency, including the price and terms of payment, is a public record subject to disclosure under this division.
(b) Any provision in a written agreement that purports to exclude a contract specified in subdivision (a) from disclosure by agreeing to consider it a confidential or proprietary record of the vendor is void and unenforceable as a matter of law.
(c) This section does not require disclosure of a record that is otherwise exempt from disclosure or prohibited from disclosure pursuant to federal or state law.