checksum method
Get the checksum for the given file.
Implementation
@override
Future<String?> checksum(String path, {String algorithm = 'md5'}) {
return _attempt<String?>(null, () async {
final object = await bucket.head(_objectKey(path));
if (object == null) return null;
final normalized = algorithm.toLowerCase().replaceAll('-', '');
final checksum = object.checksums[normalized];
if (checksum != null) return checksum;
return normalized == 'md5' ? object.etag : null;
});
}