[Group 3] Enable nullable annotations for Microsoft.Extensions.Configuration

src/libraries/Microsoft.Extensions.Configuration/ref/Microsoft.Extensions.Configuration.cs

@@ -15,23 +15,24 @@ public partial class ChainedConfigurationProvider : Microsoft.Extensions.Configu
     {
         public ChainedConfigurationProvider(Microsoft.Extensions.Configuration.ChainedConfigurationSource source) { }
         public void Dispose() { }
-        public System.Collections.Generic.IEnumerable<string> GetChildKeys(System.Collections.Generic.IEnumerable<string> earlierKeys, string parentPath) { throw null; }
+        public System.Collections.Generic.IEnumerable<string> GetChildKeys(System.Collections.Generic.IEnumerable<string> earlierKeys, string? parentPath) { throw null; }
         public Microsoft.Extensions.Primitives.IChangeToken GetReloadToken() { throw null; }
         public void Load() { }
-        public void Set(string key, string value) { }
-        public bool TryGet(string key, out string value) { throw null; }
+        public void Set(string key, string? value) { }
+        public bool TryGet(string key, [System.Diagnostics.CodeAnalysis.MaybeNullWhen(false)] out string value) { throw null; }
     }
     public partial class ChainedConfigurationSource : Microsoft.Extensions.Configuration.IConfigurationSource
     {
         public ChainedConfigurationSource() { }
-        public Microsoft.Extensions.Configuration.IConfiguration Configuration { get { throw null; } set { } }
+        [System.Diagnostics.CodeAnalysis.DisallowNull]
+        public Microsoft.Extensions.Configuration.IConfiguration? Configuration { get { throw null; } set { } }
         public bool ShouldDisposeConfiguration { get { throw null; } set { } }
         public Microsoft.Extensions.Configuration.IConfigurationProvider Build(Microsoft.Extensions.Configuration.IConfigurationBuilder builder) { throw null; }
     }
     public sealed partial class ConfigurationManager : Microsoft.Extensions.Configuration.IConfigurationBuilder, Microsoft.Extensions.Configuration.IConfigurationRoot, System.IDisposable
     {
         public ConfigurationManager() { }
-        public string this[string key] { get { throw null; } set { throw null; } }
+        public string? this[string key] { get { throw null; } set { throw null; } }
         public IConfigurationSection GetSection(string key) { throw null; }
         public System.Collections.Generic.IEnumerable<IConfigurationSection> GetChildren() { throw null; }
         public void Dispose() { throw null; }
@@ -55,32 +56,32 @@ public partial class ConfigurationKeyComparer : System.Collections.Generic.IComp
     {
         public ConfigurationKeyComparer() { }
         public static Microsoft.Extensions.Configuration.ConfigurationKeyComparer Instance { get { throw null; } }
-        public int Compare(string x, string y) { throw null; }
+        public int Compare(string? x, string? y) { throw null; }
     }
     public abstract partial class ConfigurationProvider : Microsoft.Extensions.Configuration.IConfigurationProvider
     {
         protected ConfigurationProvider() { }
-        protected System.Collections.Generic.IDictionary<string, string> Data { get { throw null; } set { } }
-        public virtual System.Collections.Generic.IEnumerable<string> GetChildKeys(System.Collections.Generic.IEnumerable<string> earlierKeys, string parentPath) { throw null; }
+        protected System.Collections.Generic.IDictionary<string, string?> Data { get { throw null; } set { } }
+        public virtual System.Collections.Generic.IEnumerable<string> GetChildKeys(System.Collections.Generic.IEnumerable<string> earlierKeys, string? parentPath) { throw null; }
         public Microsoft.Extensions.Primitives.IChangeToken GetReloadToken() { throw null; }
         public virtual void Load() { }
         protected void OnReload() { }
-        public virtual void Set(string key, string value) { }
+        public virtual void Set(string key, string? value) { }
         public override string ToString() { throw null; }
-        public virtual bool TryGet(string key, out string value) { throw null; }
+        public virtual bool TryGet(string key, out string? value) { throw null; }
     }
     public partial class ConfigurationReloadToken : Microsoft.Extensions.Primitives.IChangeToken
     {
         public ConfigurationReloadToken() { }
         public bool ActiveChangeCallbacks { get { throw null; } }
         public bool HasChanged { get { throw null; } }
         public void OnReload() { }
-        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 ConfigurationRoot : Microsoft.Extensions.Configuration.IConfiguration, Microsoft.Extensions.Configuration.IConfigurationRoot, System.IDisposable
     {
         public ConfigurationRoot(System.Collections.Generic.IList<Microsoft.Extensions.Configuration.IConfigurationProvider> providers) { }
-        public string this[string key] { get { throw null; } set { } }
+        public string? this[string key] { get { throw null; } set { } }
         public System.Collections.Generic.IEnumerable<Microsoft.Extensions.Configuration.IConfigurationProvider> Providers { get { throw null; } }
         public void Dispose() { }
         public System.Collections.Generic.IEnumerable<Microsoft.Extensions.Configuration.IConfigurationSection> GetChildren() { throw null; }
@@ -91,18 +92,18 @@ public void Reload() { }
     public partial class ConfigurationSection : Microsoft.Extensions.Configuration.IConfiguration, Microsoft.Extensions.Configuration.IConfigurationSection
     {
         public ConfigurationSection(Microsoft.Extensions.Configuration.IConfigurationRoot root, string path) { }
-        public string this[string key] { get { throw null; } set { } }
+        public string? this[string key] { get { throw null; } set { } }
         public string Key { get { throw null; } }
         public string Path { get { throw null; } }
-        public string Value { get { throw null; } set { } }
+        public string? Value { get { throw null; } set { } }
         public System.Collections.Generic.IEnumerable<Microsoft.Extensions.Configuration.IConfigurationSection> GetChildren() { throw null; }
         public Microsoft.Extensions.Primitives.IChangeToken GetReloadToken() { throw null; }
         public Microsoft.Extensions.Configuration.IConfigurationSection GetSection(string key) { throw null; }
     }
     public static partial class MemoryConfigurationBuilderExtensions
     {
         public static Microsoft.Extensions.Configuration.IConfigurationBuilder AddInMemoryCollection(this Microsoft.Extensions.Configuration.IConfigurationBuilder configurationBuilder) { throw null; }
-        public static Microsoft.Extensions.Configuration.IConfigurationBuilder AddInMemoryCollection(this Microsoft.Extensions.Configuration.IConfigurationBuilder configurationBuilder, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>> initialData) { throw null; }
+        public static Microsoft.Extensions.Configuration.IConfigurationBuilder AddInMemoryCollection(this Microsoft.Extensions.Configuration.IConfigurationBuilder configurationBuilder, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string?>>? initialData) { throw null; }
     }
     public abstract partial class StreamConfigurationProvider : Microsoft.Extensions.Configuration.ConfigurationProvider
     {
@@ -114,23 +115,24 @@ public override void Load() { }
     public abstract partial class StreamConfigurationSource : Microsoft.Extensions.Configuration.IConfigurationSource
     {
         protected StreamConfigurationSource() { }
-        public System.IO.Stream Stream { get { throw null; } set { } }
+        [System.Diagnostics.CodeAnalysis.DisallowNull]
+        public System.IO.Stream? Stream { get { throw null; } set { } }
         public abstract Microsoft.Extensions.Configuration.IConfigurationProvider Build(Microsoft.Extensions.Configuration.IConfigurationBuilder builder);
     }
 }
 namespace Microsoft.Extensions.Configuration.Memory
 {
-    public partial class MemoryConfigurationProvider : Microsoft.Extensions.Configuration.ConfigurationProvider, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>>, System.Collections.IEnumerable
+    public partial class MemoryConfigurationProvider : Microsoft.Extensions.Configuration.ConfigurationProvider, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string?>>, System.Collections.IEnumerable
     {
         public MemoryConfigurationProvider(Microsoft.Extensions.Configuration.Memory.MemoryConfigurationSource source) { }
-        public void Add(string key, string value) { }
-        public System.Collections.Generic.IEnumerator<System.Collections.Generic.KeyValuePair<string, string>> GetEnumerator() { throw null; }
+        public void Add(string key, string? value) { }
+        public System.Collections.Generic.IEnumerator<System.Collections.Generic.KeyValuePair<string, string?>> GetEnumerator() { throw null; }
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { throw null; }
     }
     public partial class MemoryConfigurationSource : Microsoft.Extensions.Configuration.IConfigurationSource
     {
         public MemoryConfigurationSource() { }
-        public System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>> InitialData { get { throw null; } set { } }
+        public System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string?>>? InitialData { get { throw null; } set { } }
         public Microsoft.Extensions.Configuration.IConfigurationProvider Build(Microsoft.Extensions.Configuration.IConfigurationBuilder builder) { throw null; }
     }
 }

src/libraries/Microsoft.Extensions.Configuration/ref/Microsoft.Extensions.Configuration.csproj

@@ -1,10 +1,15 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Microsoft.Extensions.Configuration.cs" />
     <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Extensions.Configuration.Abstractions\ref\Microsoft.Extensions.Configuration.Abstractions.csproj" />
     <ProjectReference Include="$(LibrariesProjectRoot)Microsoft.Extensions.Primitives\ref\Microsoft.Extensions.Primitives.csproj" />
   </ItemGroup>
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
+    <ProjectReference Include="$(LibrariesProjectRoot)System.Collections\ref\System.Collections.csproj" />
+    <ProjectReference Include="$(LibrariesProjectRoot)System.Runtime\ref\System.Runtime.csproj" />
+  </ItemGroup>
 </Project>

src/libraries/Microsoft.Extensions.Configuration/src/ChainedConfigurationProvider.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.Extensions.Configuration
@@ -40,7 +41,7 @@ public ChainedConfigurationProvider(ChainedConfigurationSource source)
         /// <param name="key">The key.</param>
         /// <param name="value">The value.</param>
         /// <returns><c>True</c> if a value for the specified key was found, otherwise <c>false</c>.</returns>
-        public bool TryGet(string key, out string value)
+        public bool TryGet(string key, [MaybeNullWhen(false)] out string value)
         {
             value = _config[key];
             return !string.IsNullOrEmpty(value);
@@ -51,7 +52,7 @@ public bool TryGet(string key, out string value)
         /// </summary>
         /// <param name="key">The key.</param>
         /// <param name="value">The value.</param>
-        public void Set(string key, string value) => _config[key] = value;
+        public void Set(string key, string? value) => _config[key] = value;
 
         /// <summary>
         /// Returns a change token if this provider supports change tracking, null otherwise.
@@ -74,7 +75,7 @@ public void Load() { }
         /// <returns>The child keys.</returns>
         public IEnumerable<string> GetChildKeys(
             IEnumerable<string> earlierKeys,
-            string parentPath)
+            string? parentPath)
         {
             IConfiguration section = parentPath == null ? _config : _config.GetSection(parentPath);
             var keys = new List<string>();

src/libraries/Microsoft.Extensions.Configuration/src/ChainedConfigurationSource.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
+
 namespace Microsoft.Extensions.Configuration
 {
     /// <summary>
@@ -11,7 +13,8 @@ public class ChainedConfigurationSource : IConfigurationSource
         /// <summary>
         /// The chained configuration.
         /// </summary>
-        public IConfiguration Configuration { get; set; }
+        [DisallowNull]
+        public IConfiguration? Configuration { get; set; }
 
         /// <summary>
         /// Whether the chained configuration should be disposed when the

src/libraries/Microsoft.Extensions.Configuration/src/ConfigurationKeyComparer.cs

@@ -27,7 +27,7 @@ public class ConfigurationKeyComparer : IComparer<string>
         /// <param name="x">First string.</param>
         /// <param name="y">Second string.</param>
         /// <returns>Less than 0 if x is less than y, 0 if x is equal to y and greater than 0 if x is greater than y.</returns>
-        public int Compare(string x, string y)
+        public int Compare(string? x, string? y)
         {
             string[] xParts = x?.Split(_keyDelimiterArray, StringSplitOptions.RemoveEmptyEntries) ?? Array.Empty<string>();
             string[] yParts = y?.Split(_keyDelimiterArray, StringSplitOptions.RemoveEmptyEntries) ?? Array.Empty<string>();

src/libraries/Microsoft.Extensions.Configuration/src/ConfigurationManager.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Threading;
 using Microsoft.Extensions.Configuration.Memory;
@@ -38,7 +39,7 @@ public ConfigurationManager()
         }
 
         /// <inheritdoc/>
-        public string this[string key]
+        public string? this[string key]
         {
             get
             {
@@ -338,7 +339,7 @@ public bool Remove(KeyValuePair<string, object> item)
                 return wasRemoved;
             }
 
-            public bool TryGetValue(string key, out object value)
+            public bool TryGetValue(string key, [MaybeNullWhen(false)] out object value)
             {
                 return _properties.TryGetValue(key, out value);
             }

src/libraries/Microsoft.Extensions.Configuration/src/ConfigurationProvider.cs

@@ -21,29 +21,29 @@ public abstract class ConfigurationProvider : IConfigurationProvider
         /// </summary>
         protected ConfigurationProvider()
         {
-            Data = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            Data = new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase);
         }
 
         /// <summary>
         /// The configuration key value pairs for this provider.
         /// </summary>
-        protected IDictionary<string, string> Data { get; set; }
+        protected IDictionary<string, string?> Data { get; set; }
 
         /// <summary>
         /// Attempts to find a value with the given key, returns true if one is found, false otherwise.
         /// </summary>
         /// <param name="key">The key to lookup.</param>
         /// <param name="value">The value found at key if one is found.</param>
         /// <returns>True if key has a value, false otherwise.</returns>
-        public virtual bool TryGet(string key, out string value)
+        public virtual bool TryGet(string key, out string? value)
             => Data.TryGetValue(key, out value);
 
         /// <summary>
         /// Sets a value for a given key.
         /// </summary>
         /// <param name="key">The configuration key to set.</param>
         /// <param name="value">The value to set.</param>
-        public virtual void Set(string key, string value)
+        public virtual void Set(string key, string? value)
             => Data[key] = value;
 
         /// <summary>
@@ -60,13 +60,13 @@ public virtual void Load()
         /// <returns>The list of keys for this provider.</returns>
         public virtual IEnumerable<string> GetChildKeys(
             IEnumerable<string> earlierKeys,
-            string parentPath)
+            string? parentPath)
         {
             var results = new List<string>();
 
             if (parentPath is null)
             {
-                foreach (KeyValuePair<string, string> kv in Data)
+                foreach (KeyValuePair<string, string?> kv in Data)
                 {
                     results.Add(Segment(kv.Key, 0));
                 }
@@ -75,7 +75,7 @@ public virtual IEnumerable<string> GetChildKeys(
             {
                 Debug.Assert(ConfigurationPath.KeyDelimiter == ":");
 
-                foreach (KeyValuePair<string, string> kv in Data)
+                foreach (KeyValuePair<string, string?> kv in Data)
                 {
                     if (kv.Key.Length > parentPath.Length &&
                         kv.Key.StartsWith(parentPath, StringComparison.OrdinalIgnoreCase) &&

src/libraries/Microsoft.Extensions.Configuration/src/ConfigurationReloadToken.cs

@@ -33,7 +33,7 @@ public class ConfigurationReloadToken : IChangeToken
         /// <param name="callback">The callback to invoke.</param>
         /// <param name="state">State to be passed into the callback.</param>
         /// <returns>The <see cref="CancellationToken"/> registration.</returns>
-        public IDisposable RegisterChangeCallback(Action<object> callback, object state) => _cts.Token.Register(callback, state);
+        public IDisposable RegisterChangeCallback(Action<object?> callback, object? state) => _cts.Token.Register(callback, state);
 
         /// <summary>
         /// Used to trigger the change token when a reload occurs.

src/libraries/Microsoft.Extensions.Configuration/src/ConfigurationRoot.cs

@@ -47,7 +47,7 @@ public ConfigurationRoot(IList<IConfigurationProvider> providers)
         /// </summary>
         /// <param name="key">The configuration key.</param>
         /// <returns>The configuration value.</returns>
-        public string this[string key]
+        public string? this[string key]
         {
             get => GetConfiguration(_providers, key);
             set => SetConfiguration(_providers, key, value);
@@ -111,13 +111,13 @@ public void Dispose()
             }
         }
 
-        internal static string GetConfiguration(IList<IConfigurationProvider> providers, string key)
+        internal static string? GetConfiguration(IList<IConfigurationProvider> providers, string key)
         {
             for (int i = providers.Count - 1; i >= 0; i--)
             {
                 IConfigurationProvider provider = providers[i];
 
-                if (provider.TryGet(key, out string value))
+                if (provider.TryGet(key, out string? value))
                 {
                     return value;
                 }
@@ -126,7 +126,7 @@ internal static string GetConfiguration(IList<IConfigurationProvider> providers,
             return null;
         }
 
-        internal static void SetConfiguration(IList<IConfigurationProvider> providers, string key, string value)
+        internal static void SetConfiguration(IList<IConfigurationProvider> providers, string key, string? value)
         {
             if (providers.Count == 0)
             {