protected function setupDefaults()
    {
        $defaults = (isset($this->config['defaults'])) ?
            $this->config['defaults'] :
            [];

        foreach ($defaults as $key => $value) {
            if ($key == 'images') {
                if (empty($this->images)) {
                    $this->images = $value;
                }
            } elseif ($key == 'url' && $value === null) {
                $this->setUrl(app('url')->current());
            } elseif (! empty($value) && ! array_key_exists($key, $this->properties)) {
                $this->addProperty($key, $value);
            }
        }
    }