All of the provisions of this Chapter, or any part thereof, may be waived in a bona fide collective bargaining agreement, but only if the waiver is explicitly set forth in such agreement in clear and unmistakable terms and only so long as the agreement is in effect contractually. Unilateral implementation of terms and conditions of employment by either party to a collective bargaining relationship shall not constitute, or be permitted, as a waiver of all or any part of the provisions of this Chapter.