WC_Checkout::process_order_without_payment PHP Method

    protected function process_order_without_payment($order_id)
    {
        $order = wc_get_order($order_id);
        $order->payment_complete();
        wc_empty_cart();
        if (is_ajax()) {
            wp_send_json(array('result' => 'success', 'redirect' => apply_filters('woocommerce_checkout_no_payment_needed_redirect', $order->get_checkout_order_received_url(), $order)));
        } else {
            wp_safe_redirect(apply_filters('woocommerce_checkout_no_payment_needed_redirect', $order->get_checkout_order_received_url(), $order));
            exit;
        }
    }