Lump-sum payment of small retirement income.

For any municipality, chapter plan, local law municipality, or local law plan under this chapter, notwithstanding any provision of the plan to the contrary, if the monthly retirement income payable to any person entitled to benefits hereunder is less than $100 or if the single-sum value of the accrued retirement income is less than $2,500 as of the date of retirement or termination of service, whichever is applicable, the board of trustees, in the exercise of its discretion, may specify that the actuarial equivalent of such retirement income be paid in a lump sum.