Also please make the constructor in line with [DiskFree::__construct()](https://github.com/zendframework/ZendDiagnostics/blob/master/src/ZendDiagnostics/Check/DiskFree.php#L121). For example, make path default to `$path = '/'` and [add type checks](https://github.com/zendframework/ZendDiagnostics/blob/master/src/ZendDiagnostics/Check/DiskFree.php#L123-L139)