§ 2593. Defense and indemnification. The authority shall not execute any of its powers, except as necessary to commence its corporate existence, until it has elected to make the provision of section eighteen of the public officers law applicable to its employees (as such term is defined in section eighteen of the public officers law) pursuant to subdivision two of such section; provided, however, that nothing contained within this section shall be deemed to permit the authority to extend the provisions of section eighteen of the public officers law upon any independent contractor.