public function cancel()
    {
        $url = $this->getEntityUrl() . $this->id . '/cancel';

        return $this->request(Requests::POST, $url);
    }
public function cancel()
    {
        $url = $this->getEntityUrl() . $this->id . '/cancel';

        return $this->request(Requests::POST, $url);
    }
public function cancel ( ) { $ url = $ this -> getEntityUrl ( ) . $ this -> id . '/cancel' ; return $ this -> request ( Requests :: POST , $ url ) ; }
Cancels issued invoice

@return Invoice
Cancels issued invoice