It is intended that the provisions of this subtitle be construed and administered in a manner that the retirement system’s benefit plan will be considered a qualified plan under Section 401(a) of the Internal Revenue Code of 1986 (26 U.S.C. § 401). The board of trustees may adopt rules that modify the plan to the extent the board considers necessary for the retirement system to be considered a qualified plan. Rules adopted by the board of trustees relating to plan qualification issues are considered a part of the plan.