public function setContentClass()
    {
        $delivery = $this->getCurrentInstance();
        $contentClass = $this->getClass($this->getRequestParameter('model'));

        if (is_null($this->getClassService()->getContent($delivery))) {
            $content = $this->getClassService()->createContent($delivery, $contentClass);
            $success = true;
        } else {
            $this->logWarning('Content already defined, cannot be replaced');
            $success = false;
        }
        $this->returnJson(array(
            'success' => $success
        ));
    }