Communications in collective negotiations between a party to such negotiations and its negotiator(s) shall be deemed confidential in cases before the board, a director or a director’s designee to the same extent that such communications would be subject to an attorney-client privilege if the negotiator(s) were an attorney. No administrative law judge shall accept evidence regarding such communications during any proceeding subject to this Chapter except under circumstances where it would be admissible if the negotiator(s) were an attorney.