A resolution of issuance may include a convenant that the department will at all times use its best efforts to maintain the powers, functions, duties, and obligations reposed in it pursuant to law at the time of adoption of such resolution, and that it will not at any time voluntarily do, suffer, or permit any act or thing, the effect of which would be to hinder, delay, or imperil the payment of the indebtedness evidenced by any of the revenue bonds or the performance or observance of any of the covenants contained in such resolution.