; or (B) to retaliate or threaten to retaliate against an employee for refusing to undertake or promise not to pursue, bring, join, litigate, or support any kind of joint, class, or collective legal action arising from or relating to the employment of such employee: Provided , That any agreement that violates this paragraph or results from a violation of this paragraph shall be to such extent unenforceable and void: Provided further , That this paragraph shall not apply to any agreement embodied in or expressly permitted by a contract between an employer and a labor organization. . 6. Effective date This Act, and the amendments made by this Act, shall take effect on the date of enactment of this Act and shall apply with respect to any dispute or claim that arises on or after such date, including any dispute or claim to which an agreement predating such date applies.