# System.IO

``` diff
 namespace System.IO {
     public static class FileSystemAclExtensions {
-        public static FileStream Create(this FileInfo fileInfo, FileMode mode, FileSystemRights rights, FileShare share, int bufferSize, FileOptions options, FileSecurity fileSecurity);
+        public static FileStream Create(this FileInfo fileInfo, FileMode mode, FileSystemRights rights, FileShare share, int bufferSize, FileOptions options, FileSecurity? fileSecurity);
     }
     public static class Path {
+        public static bool Exists(string? path);
     }
     public class StreamReader : TextReader {
+        public override ValueTask<string?> ReadLineAsync(CancellationToken cancellationToken);
+        public override Task<string> ReadToEndAsync(CancellationToken cancellationToken);
     }
     public class StringReader : TextReader {
+        public override ValueTask<string?> ReadLineAsync(CancellationToken cancellationToken);
+        public override Task<string> ReadToEndAsync(CancellationToken cancellationToken);
     }
     public abstract class TextReader : MarshalByRefObject, IDisposable {
+        public virtual ValueTask<string?> ReadLineAsync(CancellationToken cancellationToken);
+        public virtual Task<string> ReadToEndAsync(CancellationToken cancellationToken);
     }
 }
```

