50 ILCS 455/7

The bonds shall bear the signatures of such officers of the authority as may be designated in the resolution or ordinance authorizing such bonds and such signatures shall be the valid and binding signatures of the officers of the authority, notwithstanding that before the delivery thereof and payments therefor any or all of the persons whose signatures appear thereon have ceased to be officers of the authority issuing such bonds. The validity of the bonds is not dependent on nor affected by the validity or regularity of any proceedings relating to the acquisition, purchase, construction, reconstruction, improvement, equipping, betterment or extension of the facility for which the bonds are issued. The resolution or ordinance authorizing the bonds may provide that the bonds shall contain a recital that they are issued pursuant to this Act, which recital shall be conclusive evidence of their validity and of the regularity of their issuance.