protected static function getHttpClient($cacheDir)
	{
		if (!isset(self::$client) || self::$clientCacheDir !== $cacheDir)
		{
			self::$client = (isset($cacheDir)) ? Http::getCachingClient($cacheDir) : Http::getClient();
			self::$clientCacheDir = $cacheDir;
		}

		return self::$client;
	}