Refunding bonds may be exchanged for and in payment and discharge of any of the outstanding obligations being refunded. The refunding bonds may be exchanged for a like, greater, or smaller principal amount of the bonds being refunded as the issuing agency‘s board may determine in its discretion. The holder or holders of the bonds being refunded need not pay accrued interest on the refunding bonds if and to the extent that interest is due or accrued and unpaid on the bonds being refunded and to be surrendered.