protected function generatePropertiesLines()
    {
        $code = array();
        foreach ($this->properties as $property) {
            $property->setIndentationString($this->getIndentationString());
            $property->setIndentationLevel($this->getIndentationLevel() + 1);
            $code[] = $property->generate();
            $code[] = null;
        }

        return $code;
    }