protected function doLoadMetadata($metaType, $key)
    {
        if (isset($this->arrayCache[$metaType][$key])) {
            return $this->arrayCache[$metaType][$key];
        }
        $path = $this->getFilePath($metaType, $key);

        if (null === $path) {
            return null;
        }

        $loadMethod = $this->getLoadMethod($metaType);
        $metadata = $this->$loadMethod($key, $path);
        $this->arrayCache[$metaType][$key] = $metadata;
        return $this->arrayCache[$metaType][$key];
    }