public function __construct(?string $username = null, ?string $password = null, ?string $wsdl_url = null) 	{ 		$this->wsdlUrl = $wsdl_url ?? setting('wsdl_url'); 		$this->auth = [ 			'korisnik' => $username ?? setting('qiqo_username'), 			'lozinka' => $password ?? setting('qiqo_password'), 		]; 	}