It shall be an unfair labor practice for any employee organization and any employer to enter into any contract or agreement, express or implied, whereby the employer ceases or refrains or agrees to cease or refrain from handling, using, selling, transporting, or otherwise dealing in the products of any other person, or to cease doing business with any other person, and any contract or agreement entered into before or after enactment of this chapter containing such an agreement shall be to that extent unenforceable and void. (Added 1997, No. 92 (Adj. Sess.), § 9.)