public function getConfig()
    {
        if ($this->config === null) {
            $path = $this->getInputDirectory() . '/makedocs.json';
            if (!is_file($path)) {
                throw new \RuntimeException('The input directory does not contain a makedocs.json file.');
            }

            $data = json_decode(file_get_contents($path));
            if (!$data) {
                throw new \RuntimeException('The JSON could not be loaded.');
            }

            $this->config = new Config((array)$data);
        }
        return $this->config;
    }