public BucketService(
     IObjectIo io,
     IConfigurationManager configMgr)
 {
     _io        = io ?? throw new ArgumentNullException(nameof(io));
     _configMgr = configMgr ?? throw new ArgumentNullException(nameof(configMgr));
 }
 public ConfigurationManager(
     IObjectIo io)
 {
     _io     = io ?? throw new ArgumentNullException(nameof(io));
     _config = new Configuration();
 }