Under no circumstances shall any bonds or certificates issued by the authority or any other obligation of the authority be or become an indebtedness or obligation of the State of Nebraska, or of any other political subdivision or body corporate and politic or of any municipality within the state, nor shall any such bond, certificate, or obligation be or become an indebtedness of the authority within the purview of any constitutional limitation or provision, and it shall be plainly stated on the face of each bond and certificate that it does not constitute such an indebtedness or obligation but is payable solely from revenue and income as aforesaid, including such tax revenue as may be received, as herein provided.