Authorizing the Board of Trustees for the State Retirement and Pension System to require retirees who are under normal retirement age and are receiving a disability retirement allowance to undergo a medical examination if good cause exists; authorizing the Board of Trustees to suspend a disability retirement allowance if the Board finds that a disability retiree is no longer mentally or physically incapacitated for the further performance of the normal duties of the position of the retiree at the time of retirement; etc.