From ef86a4d7992a3731071d0321f800329792ceaa6d Mon Sep 17 00:00:00 2001
From: Maksym Koshovyi <maximkoshevoi61@gmail.com>
Date: Sat, 14 Aug 2021 17:01:18 +0300
Subject: [PATCH 1/7] Annotate src

---
 .../src/IFileInfo.cs                                        | 2 +-
 .../src/IFileProvider.cs                                    | 6 +++---
 .../Microsoft.Extensions.FileProviders.Abstractions.csproj  | 1 +
 .../src/NotFoundDirectoryContents.cs                        | 2 +-
 .../src/NotFoundFileInfo.cs                                 | 4 +++-
 .../src/NullChangeToken.cs                                  | 2 +-
 .../src/NullFileProvider.cs                                 | 6 +++---
 7 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
index d1f620c211a986..08b364ca2d8a46 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
@@ -24,7 +24,7 @@ public interface IFileInfo
         /// <summary>
         /// The path to the file, including the file name. Return null if the file is not directly accessible.
         /// </summary>
-        string PhysicalPath { get; }
+        string? PhysicalPath { get; }
 
         /// <summary>
         /// The name of the file or directory, not including any path.
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
index bce6d2d81f65e9..0f891daa67370e 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
@@ -15,20 +15,20 @@ public interface IFileProvider
         /// </summary>
         /// <param name="subpath">Relative path that identifies the file.</param>
         /// <returns>The file information. Caller must check Exists property.</returns>
-        IFileInfo GetFileInfo(string subpath);
+        IFileInfo GetFileInfo(string? subpath);
 
         /// <summary>
         /// Enumerate a directory at the given path, if any.
         /// </summary>
         /// <param name="subpath">Relative path that identifies the directory.</param>
         /// <returns>Returns the contents of the directory.</returns>
-        IDirectoryContents GetDirectoryContents(string subpath);
+        IDirectoryContents GetDirectoryContents(string? subpath);
 
         /// <summary>
         /// Creates a <see cref="IChangeToken"/> for the specified <paramref name="filter"/>.
         /// </summary>
         /// <param name="filter">Filter string used to determine what files or folders to monitor. Example: **/*.cs, *.*, subFolder/**/*.cshtml.</param>
         /// <returns>An <see cref="IChangeToken"/> that is notified when a file matching <paramref name="filter"/> is added, modified or deleted.</returns>
-        IChangeToken Watch(string filter);
+        IChangeToken Watch(string? filter);
     }
 }
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/Microsoft.Extensions.FileProviders.Abstractions.csproj b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/Microsoft.Extensions.FileProviders.Abstractions.csproj
index 07289f58670e5b..65a64a494f92ce 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/Microsoft.Extensions.FileProviders.Abstractions.csproj
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/Microsoft.Extensions.FileProviders.Abstractions.csproj
@@ -3,6 +3,7 @@
   <PropertyGroup>
     <RootNamespace>Microsoft.Extensions.FileProviders</RootNamespace>
     <TargetFrameworks>$(NetCoreAppCurrent);netstandard2.0;net461</TargetFrameworks>
+    <Nullable>enable</Nullable>
     <EnableDefaultItems>true</EnableDefaultItems>
     <PackageDescription>Abstractions of files and directories.
 
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundDirectoryContents.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundDirectoryContents.cs
index 8f4feb94eaf6c8..d9240fa8c740bd 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundDirectoryContents.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundDirectoryContents.cs
@@ -15,7 +15,7 @@ public class NotFoundDirectoryContents : IDirectoryContents
         /// <summary>
         /// A shared instance of <see cref="NotFoundDirectoryContents"/>
         /// </summary>
-        public static NotFoundDirectoryContents Singleton { get; } = new NotFoundDirectoryContents();
+        public static NotFoundDirectoryContents Singleton { get; } = new();
 
         /// <summary>
         /// Always false.
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundFileInfo.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundFileInfo.cs
index 3640a8ec424dd4..13707bae3339c3 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundFileInfo.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundFileInfo.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 
 namespace Microsoft.Extensions.FileProviders
@@ -46,13 +47,14 @@ public NotFoundFileInfo(string name)
         /// <summary>
         /// Always null.
         /// </summary>
-        public string PhysicalPath => null;
+        public string? PhysicalPath => null;
 
         /// <summary>
         /// Always throws. A stream cannot be created for non-existing file.
         /// </summary>
         /// <exception cref="FileNotFoundException">Always thrown.</exception>
         /// <returns>Does not return</returns>
+        [DoesNotReturn]
         public Stream CreateReadStream()
         {
             throw new FileNotFoundException(SR.Format(SR.FileNotExists, Name));
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullChangeToken.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullChangeToken.cs
index 19a7303555560d..b35546f2074860 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullChangeToken.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullChangeToken.cs
@@ -36,7 +36,7 @@ private NullChangeToken()
         /// <param name="callback">This parameter is ignored</param>
         /// <param name="state">This parameter is ignored</param>
         /// <returns>A disposable object that noops on dispose.</returns>
-        public IDisposable RegisterChangeCallback(Action<object> callback, object state)
+        public IDisposable RegisterChangeCallback(Action<object?> callback, object? state)
         {
             return EmptyDisposable.Instance;
         }
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
index 17c87efff85eac..1abd214b8cfc21 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
@@ -15,20 +15,20 @@ public class NullFileProvider : IFileProvider
         /// </summary>
         /// <param name="subpath">A path under the root directory. This parameter is ignored.</param>
         /// <returns>A <see cref="IDirectoryContents"/> that does not exist and does not contain any contents.</returns>
-        public IDirectoryContents GetDirectoryContents(string subpath) => NotFoundDirectoryContents.Singleton;
+        public IDirectoryContents GetDirectoryContents(string? subpath) => NotFoundDirectoryContents.Singleton;
 
         /// <summary>
         /// Locate a non-existent file.
         /// </summary>
         /// <param name="subpath">A path under the root directory.</param>
         /// <returns>A <see cref="IFileInfo"/> representing a non-existent file at the given path.</returns>
-        public IFileInfo GetFileInfo(string subpath) => new NotFoundFileInfo(subpath);
+        public IFileInfo GetFileInfo(string? subpath) => new NotFoundFileInfo(subpath);
 
         /// <summary>
         /// Returns a <see cref="IChangeToken"/> that monitors nothing.
         /// </summary>
         /// <param name="filter">Filter string used to determine what files or folders to monitor. This parameter is ignored.</param>
         /// <returns>A <see cref="IChangeToken"/> that does not register callbacks.</returns>
-        public IChangeToken Watch(string filter) => NullChangeToken.Singleton;
+        public IChangeToken Watch(string? filter) => NullChangeToken.Singleton;
     }
 }

From 3cccc99fa99a644c49db0bd3c788e2f582bdef1e Mon Sep 17 00:00:00 2001
From: Maksym Koshovyi <maximkoshevoi61@gmail.com>
Date: Sat, 14 Aug 2021 17:05:39 +0300
Subject: [PATCH 2/7] Annotate ref

---
 ...ft.Extensions.FileProviders.Abstractions.cs | 18 +++++++++---------
 ...xtensions.FileProviders.Abstractions.csproj |  1 +
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
index 3982a62c75ce9a..57caf718836aa3 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
@@ -17,14 +17,14 @@ public partial interface IFileInfo
         System.DateTimeOffset LastModified { get; }
         long Length { get; }
         string Name { get; }
-        string PhysicalPath { get; }
+        string? PhysicalPath { get; }
         System.IO.Stream CreateReadStream();
     }
     public partial interface IFileProvider
     {
-        Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string subpath);
-        Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string subpath);
-        Microsoft.Extensions.Primitives.IChangeToken Watch(string filter);
+        Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string? subpath);
+        Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string? subpath);
+        Microsoft.Extensions.Primitives.IChangeToken Watch(string? filter);
     }
     public partial class NotFoundDirectoryContents : Microsoft.Extensions.FileProviders.IDirectoryContents, System.Collections.Generic.IEnumerable<Microsoft.Extensions.FileProviders.IFileInfo>, System.Collections.IEnumerable
     {
@@ -42,7 +42,7 @@ public NotFoundFileInfo(string name) { }
         public System.DateTimeOffset LastModified { get { throw null; } }
         public long Length { get { throw null; } }
         public string Name { get { throw null; } }
-        public string PhysicalPath { get { throw null; } }
+        public string? PhysicalPath { get { throw null; } }
         public System.IO.Stream CreateReadStream() { throw null; }
     }
     public partial class NullChangeToken : Microsoft.Extensions.Primitives.IChangeToken
@@ -51,13 +51,13 @@ internal NullChangeToken() { }
         public bool ActiveChangeCallbacks { get { throw null; } }
         public bool HasChanged { get { throw null; } }
         public static Microsoft.Extensions.FileProviders.NullChangeToken Singleton { get { throw null; } }
-        public System.IDisposable RegisterChangeCallback(System.Action<object> callback, object state) { throw null; }
+        public System.IDisposable RegisterChangeCallback(System.Action<object?> callback, object? state) { throw null; }
     }
     public partial class NullFileProvider : Microsoft.Extensions.FileProviders.IFileProvider
     {
         public NullFileProvider() { }
-        public Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string subpath) { throw null; }
-        public Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string subpath) { throw null; }
-        public Microsoft.Extensions.Primitives.IChangeToken Watch(string filter) { throw null; }
+        public Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string? subpath) { throw null; }
+        public Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string? subpath) { throw null; }
+        public Microsoft.Extensions.Primitives.IChangeToken Watch(string? filter) { throw null; }
     }
 }
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.csproj b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.csproj
index bd02f83be9189b..b198cac2def854 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.csproj
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);netstandard2.0;net461</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Microsoft.Extensions.FileProviders.Abstractions.cs" />

From cc3b76315b65800a6f7ea1f80a77c052a4ebf0e4 Mon Sep 17 00:00:00 2001
From: Maksym Koshovyi <maximkoshevoi61@gmail.com>
Date: Sat, 14 Aug 2021 17:16:01 +0300
Subject: [PATCH 3/7] GetFileInfo.subpath is not null

---
 .../ref/Microsoft.Extensions.FileProviders.Abstractions.cs    | 4 ++--
 .../src/IFileProvider.cs                                      | 2 +-
 .../src/NullFileProvider.cs                                   | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
index 57caf718836aa3..a44fe674775a44 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
@@ -23,7 +23,7 @@ public partial interface IFileInfo
     public partial interface IFileProvider
     {
         Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string? subpath);
-        Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string? subpath);
+        Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string subpath);
         Microsoft.Extensions.Primitives.IChangeToken Watch(string? filter);
     }
     public partial class NotFoundDirectoryContents : Microsoft.Extensions.FileProviders.IDirectoryContents, System.Collections.Generic.IEnumerable<Microsoft.Extensions.FileProviders.IFileInfo>, System.Collections.IEnumerable
@@ -57,7 +57,7 @@ public partial class NullFileProvider : Microsoft.Extensions.FileProviders.IFile
     {
         public NullFileProvider() { }
         public Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string? subpath) { throw null; }
-        public Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string? subpath) { throw null; }
+        public Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string subpath) { throw null; }
         public Microsoft.Extensions.Primitives.IChangeToken Watch(string? filter) { throw null; }
     }
 }
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
index 0f891daa67370e..3f6cb43ce29a0a 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
@@ -15,7 +15,7 @@ public interface IFileProvider
         /// </summary>
         /// <param name="subpath">Relative path that identifies the file.</param>
         /// <returns>The file information. Caller must check Exists property.</returns>
-        IFileInfo GetFileInfo(string? subpath);
+        IFileInfo GetFileInfo(string subpath);
 
         /// <summary>
         /// Enumerate a directory at the given path, if any.
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
index 1abd214b8cfc21..1ad277592620af 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
@@ -22,7 +22,7 @@ public class NullFileProvider : IFileProvider
         /// </summary>
         /// <param name="subpath">A path under the root directory.</param>
         /// <returns>A <see cref="IFileInfo"/> representing a non-existent file at the given path.</returns>
-        public IFileInfo GetFileInfo(string? subpath) => new NotFoundFileInfo(subpath);
+        public IFileInfo GetFileInfo(string subpath) => new NotFoundFileInfo(subpath);
 
         /// <summary>
         /// Returns a <see cref="IChangeToken"/> that monitors nothing.

From 9b3df8df5f052a696c6c32e0b70e1c0d92340316 Mon Sep 17 00:00:00 2001
From: Maksym Koshovyi <maximkoshevoi61@gmail.com>
Date: Sat, 14 Aug 2021 18:30:18 +0300
Subject: [PATCH 4/7] Update Microsoft.Extensions.FileProviders.Abstractions.cs

---
 .../ref/Microsoft.Extensions.FileProviders.Abstractions.cs       | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
index a44fe674775a44..721b158e433f08 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
@@ -43,6 +43,7 @@ public NotFoundFileInfo(string name) { }
         public long Length { get { throw null; } }
         public string Name { get { throw null; } }
         public string? PhysicalPath { get { throw null; } }
+        [System.Diagnostics.CodeAnalysis.DoesNotReturn]
         public System.IO.Stream CreateReadStream() { throw null; }
     }
     public partial class NullChangeToken : Microsoft.Extensions.Primitives.IChangeToken

From 4675f8654eff5967881a2153513a6f1d1e2108e4 Mon Sep 17 00:00:00 2001
From: Maksym Koshovyi <maximkoshevoi61@gmail.com>
Date: Sat, 14 Aug 2021 20:44:00 +0300
Subject: [PATCH 5/7] Commit to rerun CI

---
 .../src/IFileInfo.cs                                            | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
index 08b364ca2d8a46..9a72b59b9e0ca5 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
@@ -12,7 +12,7 @@ namespace Microsoft.Extensions.FileProviders
     public interface IFileInfo
     {
         /// <summary>
-        /// True if resource exists in the underlying storage system.
+        /// True if resource exists in the underlying storage system
         /// </summary>
         bool Exists { get; }
 

From ec132eedbdf214341e5fe402ed1732d63f4c4c8c Mon Sep 17 00:00:00 2001
From: Maksym Koshovyi <maximkoshevoi61@gmail.com>
Date: Sat, 14 Aug 2021 20:44:10 +0300
Subject: [PATCH 6/7] Revert "Commit to rerun CI"

This reverts commit 4675f8654eff5967881a2153513a6f1d1e2108e4.
---
 .../src/IFileInfo.cs                                            | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
index 9a72b59b9e0ca5..08b364ca2d8a46 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileInfo.cs
@@ -12,7 +12,7 @@ namespace Microsoft.Extensions.FileProviders
     public interface IFileInfo
     {
         /// <summary>
-        /// True if resource exists in the underlying storage system
+        /// True if resource exists in the underlying storage system.
         /// </summary>
         bool Exists { get; }
 

From cb6103abe1c1b715dd52e163e2522b1ad44545a4 Mon Sep 17 00:00:00 2001
From: Maksym Koshovyi <maximkoshevoi61@gmail.com>
Date: Wed, 25 Aug 2021 01:59:57 +0300
Subject: [PATCH 7/7] subpath is non-nullable

---
 .../Microsoft.Extensions.FileProviders.Abstractions.cs    | 8 ++++----
 .../src/IFileProvider.cs                                  | 4 ++--
 .../src/NullFileProvider.cs                               | 4 ++--
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
index 721b158e433f08..8d3d62bb9c8734 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/ref/Microsoft.Extensions.FileProviders.Abstractions.cs
@@ -22,9 +22,9 @@ public partial interface IFileInfo
     }
     public partial interface IFileProvider
     {
-        Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string? subpath);
+        Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string subpath);
         Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string subpath);
-        Microsoft.Extensions.Primitives.IChangeToken Watch(string? filter);
+        Microsoft.Extensions.Primitives.IChangeToken Watch(string filter);
     }
     public partial class NotFoundDirectoryContents : Microsoft.Extensions.FileProviders.IDirectoryContents, System.Collections.Generic.IEnumerable<Microsoft.Extensions.FileProviders.IFileInfo>, System.Collections.IEnumerable
     {
@@ -57,8 +57,8 @@ internal NullChangeToken() { }
     public partial class NullFileProvider : Microsoft.Extensions.FileProviders.IFileProvider
     {
         public NullFileProvider() { }
-        public Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string? subpath) { throw null; }
+        public Microsoft.Extensions.FileProviders.IDirectoryContents GetDirectoryContents(string subpath) { throw null; }
         public Microsoft.Extensions.FileProviders.IFileInfo GetFileInfo(string subpath) { throw null; }
-        public Microsoft.Extensions.Primitives.IChangeToken Watch(string? filter) { throw null; }
+        public Microsoft.Extensions.Primitives.IChangeToken Watch(string filter) { throw null; }
     }
 }
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
index 3f6cb43ce29a0a..bce6d2d81f65e9 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/IFileProvider.cs
@@ -22,13 +22,13 @@ public interface IFileProvider
         /// </summary>
         /// <param name="subpath">Relative path that identifies the directory.</param>
         /// <returns>Returns the contents of the directory.</returns>
-        IDirectoryContents GetDirectoryContents(string? subpath);
+        IDirectoryContents GetDirectoryContents(string subpath);
 
         /// <summary>
         /// Creates a <see cref="IChangeToken"/> for the specified <paramref name="filter"/>.
         /// </summary>
         /// <param name="filter">Filter string used to determine what files or folders to monitor. Example: **/*.cs, *.*, subFolder/**/*.cshtml.</param>
         /// <returns>An <see cref="IChangeToken"/> that is notified when a file matching <paramref name="filter"/> is added, modified or deleted.</returns>
-        IChangeToken Watch(string? filter);
+        IChangeToken Watch(string filter);
     }
 }
diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
index 1ad277592620af..17c87efff85eac 100644
--- a/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
+++ b/src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs
@@ -15,7 +15,7 @@ public class NullFileProvider : IFileProvider
         /// </summary>
         /// <param name="subpath">A path under the root directory. This parameter is ignored.</param>
         /// <returns>A <see cref="IDirectoryContents"/> that does not exist and does not contain any contents.</returns>
-        public IDirectoryContents GetDirectoryContents(string? subpath) => NotFoundDirectoryContents.Singleton;
+        public IDirectoryContents GetDirectoryContents(string subpath) => NotFoundDirectoryContents.Singleton;
 
         /// <summary>
         /// Locate a non-existent file.
@@ -29,6 +29,6 @@ public class NullFileProvider : IFileProvider
         /// </summary>
         /// <param name="filter">Filter string used to determine what files or folders to monitor. This parameter is ignored.</param>
         /// <returns>A <see cref="IChangeToken"/> that does not register callbacks.</returns>
-        public IChangeToken Watch(string? filter) => NullChangeToken.Singleton;
+        public IChangeToken Watch(string filter) => NullChangeToken.Singleton;
     }
 }