public function setSimpleChoices(SimpleChoiceCollection $simpleChoices)
    {
        if (count($simpleChoices) > 0) {
            $this->simpleChoices = $simpleChoices;
        } else {
            $msg = "An OrderInteraction object must be composed of at lease one SimpleChoice object, none given.";
            throw new InvalidArgumentException($msg);
        }
    }