Issuance by the authority of one or more series of bonds for one or more than one purpose shall not preclude it from issuing other bonds in connection with the same facility or facilities, any other facility or facilities, or any other purpose hereunder, but the resolution or trust indenture whereunder any subsequent bonds may be issued shall recognize and protect any prior pledge or mortgage made for any prior issue of bonds. Any issue of bonds of the authority at any time outstanding may be refunded at any time and from time to time by the authority by the issuance of its refunding bonds in such amount as the authority may deem necessary, but not exceeding the amount sufficient to refund the principal of the bonds so to be refunded together with any unpaid interest thereon and any premiums, commissions, service fees, and other expenses necessary to be paid in connection with the refunding. Any such refunding may be effected whether the bonds to be refunded then shall have matured or thereafter shall mature, either by sale of the refunding bonds and the application of the proceeds thereof to the payment of the bonds being refunded or by the exchange of the refunding bonds for the bonds being refunded with the consent of the holder or holders of the bonds being refunded, regardless of whether or not the bonds being refunded were issued in connection with the same facility or facilities, or a separate facility or facilities, or any other purpose hereunder and regardless of whether or not the bonds proposed to be refunded shall be payable on the same date or different dates or shall be due serially or otherwise.