N.J. Stat. § 40:48-8.25b
In any municipality in which the provisions of P.L. 1947, c. 71 (C. 40:48-8.15 et seq.) are presently operative pursuant to an ordinance and referendum thereon approving the same heretofore adopted and held in accordance with the provisions of that act, any ordinance to adopt the provisions of this amendatory and supplementary act shall, upon adoption, become operative within the municipality without any requirement to submit the same to the voters for their approval or disapproval. Such municipality may also provide and covenant by ordinance that the ordinance authorizing such tax will not be amended so as to repeal or reduce such tax while bonds entitled to the benefits of this amendatory and supplementary act are outstanding with the holders of such bonds, unless the resolution authorizing such bonds shall provide otherwise. Such covenant shall constitute a valid and legally binding contract between such municipality and such holders.
N.J.S. § 40:48-8.25b