    public function add($item)
    {
        if ($item instanceof ItemInterface) {
            $this->items[] = $item;
        } else {
            $this->items[] = new PayPalItem($item);
        }
    }
The software constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component.