No member of the Authority or officer or employe thereof shall either directly or indirectly be a party to or be in any manner interested in any contract or agreement with the Authority for any matter, cause or thing whatsoever by reason whereof any liability or indebtedness shall in any way be created against such Authority. If any contract or agreement shall be made in violation of the provisions of this section the same shall be null and void and no action shall be maintained thereon against such Authority.
73 P.S. § 311