# Microsoft.Extensions.FileProviders.Physical

``` diff
 namespace Microsoft.Extensions.FileProviders.Physical {
     public class PhysicalFilesWatcher : IDisposable {
-        public PhysicalFilesWatcher(string root, FileSystemWatcher fileSystemWatcher, bool pollForChanges);
+        public PhysicalFilesWatcher(string root, FileSystemWatcher? fileSystemWatcher, bool pollForChanges);
-        public PhysicalFilesWatcher(string root, FileSystemWatcher fileSystemWatcher, bool pollForChanges, ExclusionFilters filters);
+        public PhysicalFilesWatcher(string root, FileSystemWatcher? fileSystemWatcher, bool pollForChanges, ExclusionFilters filters);
     }
     public class PollingFileChangeToken : IChangeToken {
-        public IDisposable RegisterChangeCallback(Action<object> callback, object state);
+        public IDisposable RegisterChangeCallback(Action<object?> callback, object? state);
     }
 }
```

