public function setHotspotChoices(HotspotChoiceCollection $hotspotChoices)
    {
        if (count($hotspotChoices) > 0) {
            $this->hotspotChoices = $hotspotChoices;
        } else {
            $msg = "A GraphicOrderInteraction must contain at least 1 hotspotChoice object. None given.";
            throw new InvalidArgumentException($msg);
        }
    }