If any provision of this article is determined to deprive a person of any property right which is vested and is indefeasible as of the effective date of this article, the provisions of this article shall nonetheless be effective as to any benefits or a part of any benefit under a retirement plan which shall be deemed to vest on or after the effective date of this article; and the right to receive any benefit under a retirement plan, which right shall vest on or after the effective date of this article, is hereby conditioned upon the full compliance and observance of the provisions hereof and the rendering of honorable service throughout the service in public employment or public office in respect of which such benefit is payable.