Annotate Microsoft.AspNetCore.Http with nullable attributes (#22928)

* Annotate Microsoft.AspNetCore.Http with nullable attributes

* Annotate Hosting with nullable

src/Hosting/Abstractions/ref/Microsoft.AspNetCore.Hosting.Abstractions.csproj

@@ -2,6 +2,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(DefaultNetCoreTargetFramework)</TargetFrameworks>
+    <Nullable>annotations</Nullable>
   </PropertyGroup>
   <ItemGroup Condition="'$(TargetFramework)' == '$(DefaultNetCoreTargetFramework)'">
     <Compile Include="Microsoft.AspNetCore.Hosting.Abstractions.netcoreapp.cs" />

src/Hosting/Abstractions/ref/Microsoft.AspNetCore.Hosting.Abstractions.netcoreapp.cs

@@ -93,8 +93,8 @@ namespace Microsoft.AspNetCore.Hosting
         Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureAppConfiguration(System.Action<Microsoft.AspNetCore.Hosting.WebHostBuilderContext, Microsoft.Extensions.Configuration.IConfigurationBuilder> configureDelegate);
         Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureServices(System.Action<Microsoft.AspNetCore.Hosting.WebHostBuilderContext, Microsoft.Extensions.DependencyInjection.IServiceCollection> configureServices);
         Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureServices(System.Action<Microsoft.Extensions.DependencyInjection.IServiceCollection> configureServices);
-        string GetSetting(string key);
+        string? GetSetting(string key);
-        Microsoft.AspNetCore.Hosting.IWebHostBuilder UseSetting(string key, string value);
+        Microsoft.AspNetCore.Hosting.IWebHostBuilder UseSetting(string key, string? value);
     }
     public partial interface IWebHostEnvironment : Microsoft.Extensions.Hosting.IHostEnvironment
     {

src/Hosting/Abstractions/src/IWebHostBuilder.cs

@@ -50,7 +50,7 @@ namespace Microsoft.AspNetCore.Hosting
         /// </summary>
         /// <param name="key">The key of the setting to look up.</param>
         /// <returns>The value the setting currently contains.</returns>
-        string GetSetting(string key);
+        string? GetSetting(string key);
 
         /// <summary>
         /// Add or replace a setting in the configuration.
@@ -58,6 +58,6 @@ namespace Microsoft.AspNetCore.Hosting
         /// <param name="key">The key of the setting to add or replace.</param>
         /// <param name="value">The value of the setting to add or replace.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        IWebHostBuilder UseSetting(string key, string value);
+        IWebHostBuilder UseSetting(string key, string? value);
     }
-}
+}

src/Hosting/Abstractions/src/Microsoft.AspNetCore.Hosting.Abstractions.csproj

@@ -8,6 +8,7 @@
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore;hosting</PackageTags>
     <IsPackable>false</IsPackable>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>

src/Hosting/Abstractions/src/WebHostBuilderContext.cs

@@ -13,11 +13,11 @@ namespace Microsoft.AspNetCore.Hosting
         /// <summary>
         /// The <see cref="IWebHostEnvironment" /> initialized by the <see cref="IWebHost" />.
         /// </summary>
-        public IWebHostEnvironment HostingEnvironment { get; set; }
+        public IWebHostEnvironment HostingEnvironment { get; set; } = default!;
 
         /// <summary>
         /// The <see cref="IConfiguration" /> containing the merged configuration of the application and the <see cref="IWebHost" />.
         /// </summary>
-        public IConfiguration Configuration { get; set; }
+        public IConfiguration Configuration { get; set; } = default!;
     }
 }

src/Http/Http.Abstractions/ref/Microsoft.AspNetCore.Http.Abstractions.netcoreapp.cs

@@ -14,7 +14,7 @@ namespace Microsoft.AspNetCore.Builder
     public partial interface IApplicationBuilder
     {
         System.IServiceProvider ApplicationServices { get; set; }
-        System.Collections.Generic.IDictionary<string, object> Properties { get; }
+        System.Collections.Generic.IDictionary<string, object?> Properties { get; }
         Microsoft.AspNetCore.Http.Features.IFeatureCollection ServerFeatures { get; }
         Microsoft.AspNetCore.Http.RequestDelegate Build();
         Microsoft.AspNetCore.Builder.IApplicationBuilder New();
@@ -108,13 +108,13 @@ namespace Microsoft.AspNetCore.Http
     public abstract partial class ConnectionInfo
     {
         protected ConnectionInfo() { }
-        public abstract System.Security.Cryptography.X509Certificates.X509Certificate2 ClientCertificate { get; set; }
+        public abstract System.Security.Cryptography.X509Certificates.X509Certificate2? ClientCertificate { get; set; }
         public abstract string Id { get; set; }
-        public abstract System.Net.IPAddress LocalIpAddress { get; set; }
+        public abstract System.Net.IPAddress? LocalIpAddress { get; set; }
         public abstract int LocalPort { get; set; }
-        public abstract System.Net.IPAddress RemoteIpAddress { get; set; }
+        public abstract System.Net.IPAddress? RemoteIpAddress { get; set; }
         public abstract int RemotePort { get; set; }
-        public abstract System.Threading.Tasks.Task<System.Security.Cryptography.X509Certificates.X509Certificate2> GetClientCertificateAsync(System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken));
+        public abstract System.Threading.Tasks.Task<System.Security.Cryptography.X509Certificates.X509Certificate2?> GetClientCertificateAsync(System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken));
     }
     public partial class CookieBuilder
     {
@@ -231,7 +231,7 @@ namespace Microsoft.AspNetCore.Http
         public abstract System.Threading.CancellationToken RequestAborted { get; set; }
         public abstract System.IServiceProvider RequestServices { get; set; }
         public abstract Microsoft.AspNetCore.Http.HttpResponse Response { get; }
-        public abstract Microsoft.AspNetCore.Http.ISession? Session { get; set; }
+        public abstract Microsoft.AspNetCore.Http.ISession Session { get; set; }
         public abstract string TraceIdentifier { get; set; }
         public abstract System.Security.Claims.ClaimsPrincipal User { get; set; }
         public abstract Microsoft.AspNetCore.Http.WebSocketManager WebSockets { get; }
@@ -326,7 +326,7 @@ namespace Microsoft.AspNetCore.Http
     }
     public partial interface IHttpContextAccessor
     {
-        Microsoft.AspNetCore.Http.HttpContext HttpContext { get; set; }
+        Microsoft.AspNetCore.Http.HttpContext? HttpContext { get; set; }
     }
     public partial interface IHttpContextFactory
     {

src/Http/Http.Abstractions/src/ConnectionInfo.cs

@@ -15,16 +15,16 @@ namespace Microsoft.AspNetCore.Http
         /// </summary>
         public abstract string Id { get; set; }
 
-        public abstract IPAddress RemoteIpAddress { get; set; }
+        public abstract IPAddress? RemoteIpAddress { get; set; }
 
         public abstract int RemotePort { get; set; }
 
-        public abstract IPAddress LocalIpAddress { get; set; }
+        public abstract IPAddress? LocalIpAddress { get; set; }
 
         public abstract int LocalPort { get; set; }
 
-        public abstract X509Certificate2 ClientCertificate { get; set; }
+        public abstract X509Certificate2? ClientCertificate { get; set; }
 
-        public abstract Task<X509Certificate2> GetClientCertificateAsync(CancellationToken cancellationToken = new CancellationToken());
+        public abstract Task<X509Certificate2?> GetClientCertificateAsync(CancellationToken cancellationToken = new CancellationToken());
     }
 }

src/Http/Http.Abstractions/src/HttpContext.cs

@@ -68,7 +68,7 @@ namespace Microsoft.AspNetCore.Http
         /// <summary>
         /// Gets or sets the object used to manage user session data for this request.
         /// </summary>
-        public abstract ISession? Session { get; set; }
+        public abstract ISession Session { get; set; }
 
         /// <summary>
         /// Aborts the connection underlying this request.

src/Http/Http.Abstractions/src/IApplicationBuilder.cs

@@ -26,7 +26,7 @@ namespace Microsoft.AspNetCore.Builder
         /// <summary>
         /// Gets a key/value collection that can be used to share data between middleware.
         /// </summary>
-        IDictionary<string, object> Properties { get; }
+        IDictionary<string, object?> Properties { get; }
 
         /// <summary>
         /// Adds a middleware delegate to the application's request pipeline.

src/Http/Http.Abstractions/src/IHttpContextAccessor.cs

@@ -15,6 +15,6 @@ namespace Microsoft.AspNetCore.Http
         /// <summary>
         /// Gets or sets the current <see cref="HttpContext"/>. Returns <see langword="null" /> if there is no active <see cref="HttpContext" />.
         /// </summary>
-        HttpContext HttpContext { get; set; }
+        HttpContext? HttpContext { get; set; }
     }
 }

src/Http/Http.Features/ref/Microsoft.AspNetCore.Http.Features.netcoreapp.cs

@@ -38,8 +38,8 @@ namespace Microsoft.AspNetCore.Http
     }
     public partial interface IFormFileCollection : System.Collections.Generic.IEnumerable<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.Generic.IReadOnlyCollection<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.IEnumerable
     {
-        Microsoft.AspNetCore.Http.IFormFile this[string name] { get; }
+        Microsoft.AspNetCore.Http.IFormFile? this[string name] { get; }
-        Microsoft.AspNetCore.Http.IFormFile GetFile(string name);
+        Microsoft.AspNetCore.Http.IFormFile? GetFile(string name);
         System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Http.IFormFile> GetFiles(string name);
     }
     public partial interface IHeaderDictionary : System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, Microsoft.Extensions.Primitives.StringValues>>, System.Collections.Generic.IDictionary<string, Microsoft.Extensions.Primitives.StringValues>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, Microsoft.Extensions.Primitives.StringValues>>, System.Collections.IEnumerable
@@ -58,10 +58,10 @@ namespace Microsoft.AspNetCore.Http
     public partial interface IRequestCookieCollection : System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>>, System.Collections.IEnumerable
     {
         int Count { get; }
-        string this[string key] { get; }
+        string? this[string key] { get; }
         System.Collections.Generic.ICollection<string> Keys { get; }
         bool ContainsKey(string key);
-        bool TryGetValue(string key, out string value);
+        bool TryGetValue(string key, [System.Diagnostics.CodeAnalysis.MaybeNullWhenAttribute(false)] out string? value);
     }
     public partial interface IResponseCookies
     {
@@ -121,8 +121,8 @@ namespace Microsoft.AspNetCore.Http.Features
         public FeatureReferences(Microsoft.AspNetCore.Http.Features.IFeatureCollection collection) { throw null; }
         public Microsoft.AspNetCore.Http.Features.IFeatureCollection Collection { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
         public int Revision { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
-        public TFeature Fetch<TFeature>([System.Diagnostics.CodeAnalysis.AllowNullAttribute, System.Diagnostics.CodeAnalysis.MaybeNullAttribute] ref TFeature cached, System.Func<Microsoft.AspNetCore.Http.Features.IFeatureCollection, TFeature> factory) where TFeature : class { throw null; }
+        public TFeature Fetch<TFeature>([System.Diagnostics.CodeAnalysis.AllowNullAttribute, System.Diagnostics.CodeAnalysis.MaybeNullAttribute] ref TFeature cached, System.Func<Microsoft.AspNetCore.Http.Features.IFeatureCollection, TFeature> factory) where TFeature : class? { throw null; }
-        [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]public TFeature Fetch<TFeature, TState>([System.Diagnostics.CodeAnalysis.AllowNullAttribute, System.Diagnostics.CodeAnalysis.MaybeNullAttribute] ref TFeature cached, TState state, System.Func<TState, TFeature> factory) where TFeature : class { throw null; }
+        [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]public TFeature Fetch<TFeature, TState>([System.Diagnostics.CodeAnalysis.AllowNullAttribute, System.Diagnostics.CodeAnalysis.MaybeNullAttribute] ref TFeature cached, TState state, System.Func<TState, TFeature> factory) where TFeature : class? { throw null; }
         [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]public void Initalize(Microsoft.AspNetCore.Http.Features.IFeatureCollection collection) { }
         [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]public void Initalize(Microsoft.AspNetCore.Http.Features.IFeatureCollection collection, int revision) { }
     }
@@ -152,7 +152,7 @@ namespace Microsoft.AspNetCore.Http.Features
     }
     public partial interface IFormFeature
     {
-        Microsoft.AspNetCore.Http.IFormCollection Form { get; set; }
+        Microsoft.AspNetCore.Http.IFormCollection? Form { get; set; }
         bool HasFormContentType { get; }
         Microsoft.AspNetCore.Http.IFormCollection ReadForm();
         System.Threading.Tasks.Task<Microsoft.AspNetCore.Http.IFormCollection> ReadFormAsync(System.Threading.CancellationToken cancellationToken);
@@ -170,9 +170,9 @@ namespace Microsoft.AspNetCore.Http.Features
     public partial interface IHttpConnectionFeature
     {
         string ConnectionId { get; set; }
-        System.Net.IPAddress LocalIpAddress { get; set; }
+        System.Net.IPAddress? LocalIpAddress { get; set; }
         int LocalPort { get; set; }
-        System.Net.IPAddress RemoteIpAddress { get; set; }
+        System.Net.IPAddress? RemoteIpAddress { get; set; }
         int RemotePort { get; set; }
     }
     public partial interface IHttpMaxRequestBodySizeFeature
@@ -225,7 +225,7 @@ namespace Microsoft.AspNetCore.Http.Features
         System.IO.Stream Body { get; set; }
         bool HasStarted { get; }
         Microsoft.AspNetCore.Http.IHeaderDictionary Headers { get; set; }
-        string ReasonPhrase { get; set; }
+        string? ReasonPhrase { get; set; }
         int StatusCode { get; set; }
         void OnCompleted(System.Func<object, System.Threading.Tasks.Task> callback, object state);
         void OnStarting(System.Func<object, System.Threading.Tasks.Task> callback, object state);
@@ -255,7 +255,7 @@ namespace Microsoft.AspNetCore.Http.Features
     }
     public partial interface IItemsFeature
     {
-        System.Collections.Generic.IDictionary<object, object> Items { get; set; }
+        System.Collections.Generic.IDictionary<object, object?> Items { get; set; }
     }
     public partial interface IQueryFeature
     {
@@ -287,8 +287,8 @@ namespace Microsoft.AspNetCore.Http.Features
     }
     public partial interface ITlsConnectionFeature
     {
-        System.Security.Cryptography.X509Certificates.X509Certificate2 ClientCertificate { get; set; }
+        System.Security.Cryptography.X509Certificates.X509Certificate2? ClientCertificate { get; set; }
-        System.Threading.Tasks.Task<System.Security.Cryptography.X509Certificates.X509Certificate2> GetClientCertificateAsync(System.Threading.CancellationToken cancellationToken);
+        System.Threading.Tasks.Task<System.Security.Cryptography.X509Certificates.X509Certificate2?> GetClientCertificateAsync(System.Threading.CancellationToken cancellationToken);
     }
     public partial interface ITlsTokenBindingFeature
     {
@@ -309,6 +309,6 @@ namespace Microsoft.AspNetCore.Http.Features.Authentication
 {
     public partial interface IHttpAuthenticationFeature
     {
-        System.Security.Claims.ClaimsPrincipal User { get; set; }
+        System.Security.Claims.ClaimsPrincipal? User { get; set; }
     }
 }

src/Http/Http.Features/ref/Microsoft.AspNetCore.Http.Features.netstandard2.0.cs

@@ -38,8 +38,8 @@ namespace Microsoft.AspNetCore.Http
     }
     public partial interface IFormFileCollection : System.Collections.Generic.IEnumerable<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.Generic.IReadOnlyCollection<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.IEnumerable
     {
-        Microsoft.AspNetCore.Http.IFormFile this[string name] { get; }
+        Microsoft.AspNetCore.Http.IFormFile? this[string name] { get; }
-        Microsoft.AspNetCore.Http.IFormFile GetFile(string name);
+        Microsoft.AspNetCore.Http.IFormFile? GetFile(string name);
         System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Http.IFormFile> GetFiles(string name);
     }
     public partial interface IHeaderDictionary : System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, Microsoft.Extensions.Primitives.StringValues>>, System.Collections.Generic.IDictionary<string, Microsoft.Extensions.Primitives.StringValues>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, Microsoft.Extensions.Primitives.StringValues>>, System.Collections.IEnumerable
@@ -58,10 +58,10 @@ namespace Microsoft.AspNetCore.Http
     public partial interface IRequestCookieCollection : System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, string>>, System.Collections.IEnumerable
     {
         int Count { get; }
-        string this[string key] { get; }
+        string? this[string key] { get; }
         System.Collections.Generic.ICollection<string> Keys { get; }
         bool ContainsKey(string key);
-        bool TryGetValue(string key, out string value);
+        bool TryGetValue(string key, out string? value);
     }
     public partial interface IResponseCookies
     {
@@ -118,8 +118,8 @@ namespace Microsoft.AspNetCore.Http.Features
         public FeatureReferences(Microsoft.AspNetCore.Http.Features.IFeatureCollection collection) { throw null; }
         public Microsoft.AspNetCore.Http.Features.IFeatureCollection Collection { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
         public int Revision { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
-        public TFeature Fetch<TFeature>(ref TFeature cached, System.Func<Microsoft.AspNetCore.Http.Features.IFeatureCollection, TFeature> factory) where TFeature : class { throw null; }
+        public TFeature Fetch<TFeature>(ref TFeature cached, System.Func<Microsoft.AspNetCore.Http.Features.IFeatureCollection, TFeature> factory) where TFeature : class? { throw null; }
-        [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]public TFeature Fetch<TFeature, TState>(ref TFeature cached, TState state, System.Func<TState, TFeature> factory) where TFeature : class { throw null; }
+        [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]public TFeature Fetch<TFeature, TState>(ref TFeature cached, TState state, System.Func<TState, TFeature> factory) where TFeature : class? { throw null; }
         [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]public void Initalize(Microsoft.AspNetCore.Http.Features.IFeatureCollection collection) { }
         [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.AggressiveInlining)]public void Initalize(Microsoft.AspNetCore.Http.Features.IFeatureCollection collection, int revision) { }
     }
@@ -148,7 +148,7 @@ namespace Microsoft.AspNetCore.Http.Features
     }
     public partial interface IFormFeature
     {
-        Microsoft.AspNetCore.Http.IFormCollection Form { get; set; }
+        Microsoft.AspNetCore.Http.IFormCollection? Form { get; set; }
         bool HasFormContentType { get; }
         Microsoft.AspNetCore.Http.IFormCollection ReadForm();
         System.Threading.Tasks.Task<Microsoft.AspNetCore.Http.IFormCollection> ReadFormAsync(System.Threading.CancellationToken cancellationToken);
@@ -166,9 +166,9 @@ namespace Microsoft.AspNetCore.Http.Features
     public partial interface IHttpConnectionFeature
     {
         string ConnectionId { get; set; }
-        System.Net.IPAddress LocalIpAddress { get; set; }
+        System.Net.IPAddress? LocalIpAddress { get; set; }
         int LocalPort { get; set; }
-        System.Net.IPAddress RemoteIpAddress { get; set; }
+        System.Net.IPAddress? RemoteIpAddress { get; set; }
         int RemotePort { get; set; }
     }
     public partial interface IHttpMaxRequestBodySizeFeature
@@ -221,7 +221,7 @@ namespace Microsoft.AspNetCore.Http.Features
         System.IO.Stream Body { get; set; }
         bool HasStarted { get; }
         Microsoft.AspNetCore.Http.IHeaderDictionary Headers { get; set; }
-        string ReasonPhrase { get; set; }
+        string? ReasonPhrase { get; set; }
         int StatusCode { get; set; }
         void OnCompleted(System.Func<object, System.Threading.Tasks.Task> callback, object state);
         void OnStarting(System.Func<object, System.Threading.Tasks.Task> callback, object state);
@@ -251,7 +251,7 @@ namespace Microsoft.AspNetCore.Http.Features
     }
     public partial interface IItemsFeature
     {
-        System.Collections.Generic.IDictionary<object, object> Items { get; set; }
+        System.Collections.Generic.IDictionary<object, object?> Items { get; set; }
     }
     public partial interface IQueryFeature
     {
@@ -283,8 +283,8 @@ namespace Microsoft.AspNetCore.Http.Features
     }
     public partial interface ITlsConnectionFeature
     {
-        System.Security.Cryptography.X509Certificates.X509Certificate2 ClientCertificate { get; set; }
+        System.Security.Cryptography.X509Certificates.X509Certificate2? ClientCertificate { get; set; }
-        System.Threading.Tasks.Task<System.Security.Cryptography.X509Certificates.X509Certificate2> GetClientCertificateAsync(System.Threading.CancellationToken cancellationToken);
+        System.Threading.Tasks.Task<System.Security.Cryptography.X509Certificates.X509Certificate2?> GetClientCertificateAsync(System.Threading.CancellationToken cancellationToken);
     }
     public partial interface ITlsTokenBindingFeature
     {
@@ -305,6 +305,6 @@ namespace Microsoft.AspNetCore.Http.Features.Authentication
 {
     public partial interface IHttpAuthenticationFeature
     {
-        System.Security.Claims.ClaimsPrincipal User { get; set; }
+        System.Security.Claims.ClaimsPrincipal? User { get; set; }
     }
 }

src/Http/Http.Features/src/Authentication/IHttpAuthenticationFeature.cs

@@ -8,6 +8,6 @@ namespace Microsoft.AspNetCore.Http.Features.Authentication
 {
     public interface IHttpAuthenticationFeature
     {
-        ClaimsPrincipal User { get; set; }
+        ClaimsPrincipal? User { get; set; }
     }
 }

src/Http/Http.Features/src/FeatureReferences.cs

@@ -62,9 +62,9 @@ namespace Microsoft.AspNetCore.Http.Features
         // Generally Fetch is called at a ratio > x4 of UpdateCached so this is a large gain
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public TFeature Fetch<TFeature, TState>(
-            [AllowNull, MaybeNull]ref TFeature cached,
+            [AllowNull, MaybeNull] ref TFeature cached,
             TState state,
-            Func<TState, TFeature> factory) where TFeature : class
+            Func<TState, TFeature> factory) where TFeature : class?
         {
             var flush = false;
             var revision = Collection?.Revision ?? ContextDisposed();
@@ -80,7 +80,7 @@ namespace Microsoft.AspNetCore.Http.Features
         }
 
         // Update and cache clearing logic, when the fast-path in Fetch isn't applicable
-        private TFeature UpdateCached<TFeature, TState>(ref TFeature cached, TState state, Func<TState, TFeature> factory, int revision, bool flush) where TFeature : class
+        private TFeature UpdateCached<TFeature, TState>(ref TFeature cached, TState state, Func<TState, TFeature> factory, int revision, bool flush) where TFeature : class?
         {
             if (flush)
             {
@@ -108,8 +108,8 @@ namespace Microsoft.AspNetCore.Http.Features
             return cached;
         }
 
-        public TFeature Fetch<TFeature>([AllowNull, MaybeNull]ref TFeature cached, Func<IFeatureCollection, TFeature> factory)
+        public TFeature Fetch<TFeature>([AllowNull, MaybeNull] ref TFeature cached, Func<IFeatureCollection, TFeature> factory)
-            where TFeature : class => Fetch(ref cached!, Collection, factory);
+            where TFeature : class? => Fetch(ref cached!, Collection, factory);
 
         private static int ContextDisposed()
         {

src/Http/Http.Features/src/IFormFeature.cs

@@ -16,12 +16,12 @@ namespace Microsoft.AspNetCore.Http.Features
         /// <summary>
         /// The parsed form, if any.
         /// </summary>
-        IFormCollection Form { get; set; }
+        IFormCollection? Form { get; set; }
 
         /// <summary>
         /// Parses the request body as a form.
         /// </summary>
-        /// <returns></returns>
+        /// <returns>The <see cref="IFormCollection"/>.</returns>
         IFormCollection ReadForm();
 
         /// <summary>

src/Http/Http.Features/src/IFormFileCollection.cs

@@ -17,7 +17,7 @@ namespace Microsoft.AspNetCore.Http
         /// <returns>
         ///	The requested file, or null if it is not present.
         /// </returns>
-        IFormFile this[string name] { get; }
+        IFormFile? this[string name] { get; }
 
         /// <summary>
         /// Gets the first file with the specified name.
@@ -26,7 +26,7 @@ namespace Microsoft.AspNetCore.Http
         /// <returns>
         ///	The requested file, or null if it is not present.
         /// </returns>
-        IFormFile GetFile(string name);
+        IFormFile? GetFile(string name);
 
         /// <summary>
         ///     Gets an <see cref="IReadOnlyList{T}" /> containing the files of the

src/Http/Http.Features/src/IHttpConnectionFeature.cs

@@ -18,12 +18,12 @@ namespace Microsoft.AspNetCore.Http.Features
         /// <summary>
         /// The IPAddress of the client making the request. Note this may be for a proxy rather than the end user.
         /// </summary>
-        IPAddress RemoteIpAddress { get; set; }
+        IPAddress? RemoteIpAddress { get; set; }
 
         /// <summary>
         /// The local IPAddress on which the request was received.
         /// </summary>
-        IPAddress LocalIpAddress { get; set; }
+        IPAddress? LocalIpAddress { get; set; }
 
         /// <summary>
         /// The remote port of the client making the request.
@@ -35,4 +35,4 @@ namespace Microsoft.AspNetCore.Http.Features
         /// </summary>
         int LocalPort { get; set; }
     }
-}
+}

src/Http/Http.Features/src/IHttpResponseFeature.cs

@@ -20,7 +20,7 @@ namespace Microsoft.AspNetCore.Http.Features
         /// <summary>
         /// The reason-phrase as defined in RFC 7230. Note this field is no longer supported by HTTP/2.
         /// </summary>
-        string ReasonPhrase { get; set; }
+        string? ReasonPhrase { get; set; }
 
         /// <summary>
         /// The response headers to send. Headers with multiple values will be emitted as multiple headers.

src/Http/Http.Features/src/IItemsFeature.cs

@@ -7,6 +7,6 @@ namespace Microsoft.AspNetCore.Http.Features
 {
     public interface IItemsFeature
     {
-        IDictionary<object, object> Items { get; set; }
+        IDictionary<object, object?> Items { get; set; }
     }
-}
+}

src/Http/Http.Features/src/IRequestCookieCollection.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Microsoft.AspNetCore.Http
 {
@@ -63,7 +64,7 @@ namespace Microsoft.AspNetCore.Http
         /// <exception cref="System.ArgumentNullException">
         ///     key is null.
         /// </exception>
-        bool TryGetValue(string key, out string value);
+        bool TryGetValue(string key, [MaybeNullWhen(false)] out string? value);
 
         /// <summary>
         ///     Gets the value with the specified key.
@@ -82,6 +83,6 @@ namespace Microsoft.AspNetCore.Http
         ///     <see cref="IDictionary{TKey, TValue}" />, as it will return <c>string.Empty</c> for missing entries
         ///     rather than throwing an Exception.
         /// </remarks>
-        string this[string key] { get; }
+        string? this[string key] { get; }
     }
 }

src/Http/Http.Features/src/ITlsConnectionFeature.cs

@@ -12,12 +12,12 @@ namespace Microsoft.AspNetCore.Http.Features
         /// <summary>
         /// Synchronously retrieves the client certificate, if any.
         /// </summary>
-        X509Certificate2 ClientCertificate { get; set; }
+        X509Certificate2? ClientCertificate { get; set; }
 
         /// <summary>
         /// Asynchronously retrieves the client certificate, if any.
         /// </summary>
         /// <returns></returns>
-        Task<X509Certificate2> GetClientCertificateAsync(CancellationToken cancellationToken);
+        Task<X509Certificate2?> GetClientCertificateAsync(CancellationToken cancellationToken);
     }
 }

src/Http/Http/ref/Microsoft.AspNetCore.Http.csproj

@@ -2,6 +2,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(DefaultNetCoreTargetFramework)</TargetFrameworks>
+    <Nullable>annotations</Nullable>
   </PropertyGroup>
   <ItemGroup Condition="'$(TargetFramework)' == '$(DefaultNetCoreTargetFramework)'">
     <Compile Include="Microsoft.AspNetCore.Http.netcoreapp.cs" />

src/Http/Http/ref/Microsoft.AspNetCore.Http.netcoreapp.cs

@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Builder
         public ApplicationBuilder(System.IServiceProvider serviceProvider) { }
         public ApplicationBuilder(System.IServiceProvider serviceProvider, object server) { }
         public System.IServiceProvider ApplicationServices { get { throw null; } set { } }
-        public System.Collections.Generic.IDictionary<string, object> Properties { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        public System.Collections.Generic.IDictionary<string, object?> Properties { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
         public Microsoft.AspNetCore.Http.Features.IFeatureCollection ServerFeatures { get { throw null; } }
         public Microsoft.AspNetCore.Http.RequestDelegate Build() { throw null; }
         public Microsoft.AspNetCore.Builder.IApplicationBuilder New() { throw null; }
@@ -26,7 +26,7 @@ namespace Microsoft.AspNetCore.Http
         public int Port { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
         public string Scheme { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
         public string UnixPipePath { get { throw null; } }
-        public override bool Equals(object obj) { throw null; }
+        public override bool Equals(object? obj) { throw null; }
         public override int GetHashCode() { throw null; }
         public static Microsoft.AspNetCore.Http.BindingAddress Parse(string address) { throw null; }
         public override string ToString() { throw null; }
@@ -40,7 +40,7 @@ namespace Microsoft.AspNetCore.Http
         public Microsoft.AspNetCore.Http.Features.FormOptions FormOptions { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
         public Microsoft.AspNetCore.Http.HttpContext HttpContext { get { throw null; } }
-        public override System.Collections.Generic.IDictionary<object, object> Items { get { throw null; } set { } }
+        public override System.Collections.Generic.IDictionary<object, object?> Items { get { throw null; } set { } }
         public override Microsoft.AspNetCore.Http.HttpRequest Request { get { throw null; } }
         public override System.Threading.CancellationToken RequestAborted { get { throw null; } set { } }
         public override System.IServiceProvider RequestServices { get { throw null; } set { } }
@@ -57,7 +57,7 @@ namespace Microsoft.AspNetCore.Http
     public partial class FormCollection : Microsoft.AspNetCore.Http.IFormCollection, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, Microsoft.Extensions.Primitives.StringValues>>, System.Collections.IEnumerable
     {
         public static readonly Microsoft.AspNetCore.Http.FormCollection Empty;
-        public FormCollection(System.Collections.Generic.Dictionary<string, Microsoft.Extensions.Primitives.StringValues> fields, Microsoft.AspNetCore.Http.IFormFileCollection files = null) { }
+        public FormCollection(System.Collections.Generic.Dictionary<string, Microsoft.Extensions.Primitives.StringValues>? fields, Microsoft.AspNetCore.Http.IFormFileCollection? files = null) { }
         public int Count { get { throw null; } }
         public Microsoft.AspNetCore.Http.IFormFileCollection Files { get { throw null; } }
         public Microsoft.Extensions.Primitives.StringValues this[string key] { get { throw null; } }
@@ -96,14 +96,14 @@ namespace Microsoft.AspNetCore.Http
     public partial class FormFileCollection : System.Collections.Generic.List<Microsoft.AspNetCore.Http.IFormFile>, Microsoft.AspNetCore.Http.IFormFileCollection, System.Collections.Generic.IEnumerable<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.Generic.IReadOnlyCollection<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Http.IFormFile>, System.Collections.IEnumerable
     {
         public FormFileCollection() { }
-        public Microsoft.AspNetCore.Http.IFormFile this[string name] { get { throw null; } }
+        public Microsoft.AspNetCore.Http.IFormFile? this[string name] { get { throw null; } }
-        public Microsoft.AspNetCore.Http.IFormFile GetFile(string name) { throw null; }
+        public Microsoft.AspNetCore.Http.IFormFile? GetFile(string name) { throw null; }
         public System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Http.IFormFile> GetFiles(string name) { throw null; }
     }
     public partial class HeaderDictionary : Microsoft.AspNetCore.Http.IHeaderDictionary, System.Collections.Generic.ICollection<System.Collections.Generic.KeyValuePair<string, Microsoft.Extensions.Primitives.StringValues>>, System.Collections.Generic.IDictionary<string, Microsoft.Extensions.Primitives.StringValues>, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, Microsoft.Extensions.Primitives.StringValues>>, System.Collections.IEnumerable
     {
         public HeaderDictionary() { }
-        public HeaderDictionary(System.Collections.Generic.Dictionary<string, Microsoft.Extensions.Primitives.StringValues> store) { }
+        public HeaderDictionary(System.Collections.Generic.Dictionary<string, Microsoft.Extensions.Primitives.StringValues>? store) { }
         public HeaderDictionary(int capacity) { }
         public long? ContentLength { get { throw null; } set { } }
         public int Count { get { throw null; } }
@@ -139,15 +139,15 @@ namespace Microsoft.AspNetCore.Http
     public partial class HttpContextAccessor : Microsoft.AspNetCore.Http.IHttpContextAccessor
     {
         public HttpContextAccessor() { }
-        public Microsoft.AspNetCore.Http.HttpContext HttpContext { get { throw null; } set { } }
+        public Microsoft.AspNetCore.Http.HttpContext? HttpContext { get { throw null; } set { } }
     }
     [System.ObsoleteAttribute("This is obsolete and will be removed in a future version. Use DefaultHttpContextFactory instead.")]
     public partial class HttpContextFactory : Microsoft.AspNetCore.Http.IHttpContextFactory
     {
         public HttpContextFactory(Microsoft.Extensions.Options.IOptions<Microsoft.AspNetCore.Http.Features.FormOptions> formOptions) { }
-        public HttpContextFactory(Microsoft.Extensions.Options.IOptions<Microsoft.AspNetCore.Http.Features.FormOptions> formOptions, Microsoft.AspNetCore.Http.IHttpContextAccessor httpContextAccessor) { }
+        public HttpContextFactory(Microsoft.Extensions.Options.IOptions<Microsoft.AspNetCore.Http.Features.FormOptions> formOptions, Microsoft.AspNetCore.Http.IHttpContextAccessor? httpContextAccessor) { }
         public HttpContextFactory(Microsoft.Extensions.Options.IOptions<Microsoft.AspNetCore.Http.Features.FormOptions> formOptions, Microsoft.Extensions.DependencyInjection.IServiceScopeFactory serviceScopeFactory) { }
-        public HttpContextFactory(Microsoft.Extensions.Options.IOptions<Microsoft.AspNetCore.Http.Features.FormOptions> formOptions, Microsoft.Extensions.DependencyInjection.IServiceScopeFactory serviceScopeFactory, Microsoft.AspNetCore.Http.IHttpContextAccessor httpContextAccessor) { }
+        public HttpContextFactory(Microsoft.Extensions.Options.IOptions<Microsoft.AspNetCore.Http.Features.FormOptions> formOptions, Microsoft.Extensions.DependencyInjection.IServiceScopeFactory serviceScopeFactory, Microsoft.AspNetCore.Http.IHttpContextAccessor? httpContextAccessor) { }
         public Microsoft.AspNetCore.Http.HttpContext Create(Microsoft.AspNetCore.Http.Features.IFeatureCollection featureCollection) { throw null; }
         public void Dispose(Microsoft.AspNetCore.Http.HttpContext httpContext) { }
     }
@@ -161,7 +161,7 @@ namespace Microsoft.AspNetCore.Http
     public partial class MiddlewareFactory : Microsoft.AspNetCore.Http.IMiddlewareFactory
     {
         public MiddlewareFactory(System.IServiceProvider serviceProvider) { }
-        public Microsoft.AspNetCore.Http.IMiddleware Create(System.Type middlewareType) { throw null; }
+        public Microsoft.AspNetCore.Http.IMiddleware? Create(System.Type middlewareType) { throw null; }
         public void Release(Microsoft.AspNetCore.Http.IMiddleware middleware) { }
     }
     public partial class QueryCollection : Microsoft.AspNetCore.Http.IQueryCollection, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string, Microsoft.Extensions.Primitives.StringValues>>, System.Collections.IEnumerable
@@ -204,7 +204,7 @@ namespace Microsoft.AspNetCore.Http
     {
         public StreamResponseBodyFeature(System.IO.Stream stream) { }
         public StreamResponseBodyFeature(System.IO.Stream stream, Microsoft.AspNetCore.Http.Features.IHttpResponseBodyFeature priorFeature) { }
-        public Microsoft.AspNetCore.Http.Features.IHttpResponseBodyFeature PriorFeature { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
+        public Microsoft.AspNetCore.Http.Features.IHttpResponseBodyFeature? PriorFeature { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
         public System.IO.Stream Stream { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } }
         public System.IO.Pipelines.PipeWriter Writer { get { throw null; } }
         [System.Diagnostics.DebuggerStepThroughAttribute]
@@ -228,7 +228,7 @@ namespace Microsoft.AspNetCore.Http.Features
         public FormFeature(Microsoft.AspNetCore.Http.HttpRequest request) { }
         public FormFeature(Microsoft.AspNetCore.Http.HttpRequest request, Microsoft.AspNetCore.Http.Features.FormOptions options) { }
         public FormFeature(Microsoft.AspNetCore.Http.IFormCollection form) { }
-        public Microsoft.AspNetCore.Http.IFormCollection Form { get { throw null; } set { } }
+        public Microsoft.AspNetCore.Http.IFormCollection? Form { get { throw null; } set { } }
         public bool HasFormContentType { get { throw null; } }
         public Microsoft.AspNetCore.Http.IFormCollection ReadForm() { throw null; }
         public System.Threading.Tasks.Task<Microsoft.AspNetCore.Http.IFormCollection> ReadFormAsync() { throw null; }
@@ -256,9 +256,9 @@ namespace Microsoft.AspNetCore.Http.Features
     {
         public HttpConnectionFeature() { }
         public string ConnectionId { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
-        public System.Net.IPAddress LocalIpAddress { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public System.Net.IPAddress? LocalIpAddress { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         public int LocalPort { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
-        public System.Net.IPAddress RemoteIpAddress { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public System.Net.IPAddress? RemoteIpAddress { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         public int RemotePort { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
     }
     public partial class HttpRequestFeature : Microsoft.AspNetCore.Http.Features.IHttpRequestFeature
@@ -291,7 +291,7 @@ namespace Microsoft.AspNetCore.Http.Features
         public System.IO.Stream Body { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         public virtual bool HasStarted { get { throw null; } }
         public Microsoft.AspNetCore.Http.IHeaderDictionary Headers { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
-        public string ReasonPhrase { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public string? ReasonPhrase { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         public int StatusCode { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         public virtual void OnCompleted(System.Func<object, System.Threading.Tasks.Task> callback, object state) { }
         public virtual void OnStarting(System.Func<object, System.Threading.Tasks.Task> callback, object state) { }
@@ -299,7 +299,7 @@ namespace Microsoft.AspNetCore.Http.Features
     public partial class ItemsFeature : Microsoft.AspNetCore.Http.Features.IItemsFeature
     {
         public ItemsFeature() { }
-        public System.Collections.Generic.IDictionary<object, object> Items { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public System.Collections.Generic.IDictionary<object, object?> Items { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
     }
     public partial class QueryFeature : Microsoft.AspNetCore.Http.Features.IQueryFeature
     {
@@ -320,7 +320,7 @@ namespace Microsoft.AspNetCore.Http.Features
     }
     public partial class RequestServicesFeature : Microsoft.AspNetCore.Http.Features.IServiceProvidersFeature, System.IAsyncDisposable, System.IDisposable
     {
-        public RequestServicesFeature(Microsoft.AspNetCore.Http.HttpContext context, Microsoft.Extensions.DependencyInjection.IServiceScopeFactory scopeFactory) { }
+        public RequestServicesFeature(Microsoft.AspNetCore.Http.HttpContext context, Microsoft.Extensions.DependencyInjection.IServiceScopeFactory? scopeFactory) { }
         public System.IServiceProvider RequestServices { get { throw null; } set { } }
         public void Dispose() { }
         public System.Threading.Tasks.ValueTask DisposeAsync() { throw null; }
@@ -328,7 +328,7 @@ namespace Microsoft.AspNetCore.Http.Features
     public partial class ResponseCookiesFeature : Microsoft.AspNetCore.Http.Features.IResponseCookiesFeature
     {
         public ResponseCookiesFeature(Microsoft.AspNetCore.Http.Features.IFeatureCollection features) { }
-        public ResponseCookiesFeature(Microsoft.AspNetCore.Http.Features.IFeatureCollection features, Microsoft.Extensions.ObjectPool.ObjectPool<System.Text.StringBuilder> builderPool) { }
+        public ResponseCookiesFeature(Microsoft.AspNetCore.Http.Features.IFeatureCollection features, Microsoft.Extensions.ObjectPool.ObjectPool<System.Text.StringBuilder>? builderPool) { }
         public Microsoft.AspNetCore.Http.IResponseCookies Cookies { get { throw null; } }
     }
     public partial class RouteValuesFeature : Microsoft.AspNetCore.Http.Features.IRouteValuesFeature
@@ -344,8 +344,8 @@ namespace Microsoft.AspNetCore.Http.Features
     public partial class TlsConnectionFeature : Microsoft.AspNetCore.Http.Features.ITlsConnectionFeature
     {
         public TlsConnectionFeature() { }
-        public System.Security.Cryptography.X509Certificates.X509Certificate2 ClientCertificate { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public System.Security.Cryptography.X509Certificates.X509Certificate2? ClientCertificate { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
-        public System.Threading.Tasks.Task<System.Security.Cryptography.X509Certificates.X509Certificate2> GetClientCertificateAsync(System.Threading.CancellationToken cancellationToken) { throw null; }
+        public System.Threading.Tasks.Task<System.Security.Cryptography.X509Certificates.X509Certificate2?> GetClientCertificateAsync(System.Threading.CancellationToken cancellationToken) { throw null; }
     }
 }
 namespace Microsoft.AspNetCore.Http.Features.Authentication
@@ -353,7 +353,7 @@ namespace Microsoft.AspNetCore.Http.Features.Authentication
     public partial class HttpAuthenticationFeature : Microsoft.AspNetCore.Http.Features.Authentication.IHttpAuthenticationFeature
     {
         public HttpAuthenticationFeature() { }
-        public System.Security.Claims.ClaimsPrincipal User { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public System.Security.Claims.ClaimsPrincipal? User { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
     }
 }
 namespace Microsoft.Extensions.DependencyInjection

src/Http/Http/src/BindingAddress.cs

@@ -12,10 +12,10 @@ namespace Microsoft.AspNetCore.Http
     {
         private const string UnixPipeHostPrefix = "unix:/";
 
-        public string Host { get; private set; }
+        public string Host { get; private set; } = default!;
-        public string PathBase { get; private set; }
+        public string PathBase { get; private set; } = default!;
         public int Port { get; internal set; }
-        public string Scheme { get; private set; }
+        public string Scheme { get; private set; } = default!;
 
         public bool IsUnixPipe
         {
@@ -62,7 +62,7 @@ namespace Microsoft.AspNetCore.Http
             return ToString().GetHashCode();
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             var other = obj as BindingAddress;
             if (other == null)

src/Http/Http/src/Builder/ApplicationBuilder.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
@@ -20,7 +21,7 @@ namespace Microsoft.AspNetCore.Builder
 
         public ApplicationBuilder(IServiceProvider serviceProvider)
         {
-            Properties = new Dictionary<string, object>(StringComparer.Ordinal);
+            Properties = new Dictionary<string, object?>(StringComparer.Ordinal);
             ApplicationServices = serviceProvider;
         }
 
@@ -32,14 +33,14 @@ namespace Microsoft.AspNetCore.Builder
 
         private ApplicationBuilder(ApplicationBuilder builder)
         {
-            Properties = new CopyOnWriteDictionary<string, object>(builder.Properties, StringComparer.Ordinal);
+            Properties = new CopyOnWriteDictionary<string, object?>(builder.Properties, StringComparer.Ordinal);
         }
 
         public IServiceProvider ApplicationServices
         {
             get
             {
-                return GetProperty<IServiceProvider>(ApplicationServicesKey);
+                return GetProperty<IServiceProvider>(ApplicationServicesKey)!;
             }
             set
             {
@@ -51,16 +52,16 @@ namespace Microsoft.AspNetCore.Builder
         {
             get
             {
-                return GetProperty<IFeatureCollection>(ServerFeaturesKey);
+                return GetProperty<IFeatureCollection>(ServerFeaturesKey)!;
             }
         }
 
-        public IDictionary<string, object> Properties { get; }
+        public IDictionary<string, object?> Properties { get; }
 
+        [return: MaybeNull]
         private T GetProperty<T>(string key)
         {
-            object value;
+            return Properties.TryGetValue(key, out var value) ? (T)value : default(T);
-            return Properties.TryGetValue(key, out value) ? (T)value : default(T);
         }
 
         private void SetProperty<T>(string key, T value)
@@ -90,7 +91,7 @@ namespace Microsoft.AspNetCore.Builder
                 if (endpointRequestDelegate != null)
                 {
                     var message =
-                        $"The request reached the end of the pipeline without executing the endpoint: '{endpoint.DisplayName}'. " +
+                        $"The request reached the end of the pipeline without executing the endpoint: '{endpoint!.DisplayName}'. " +
                         $"Please register the EndpointMiddleware using '{nameof(IApplicationBuilder)}.UseEndpoints(...)' if using " +
                         $"routing.";
                     throw new InvalidOperationException(message);

src/Http/Http/src/DefaultHttpContext.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Security.Claims;
 using System.Threading;
@@ -24,7 +25,7 @@ namespace Microsoft.AspNetCore.Http
         private readonly static Func<IFeatureCollection, IHttpAuthenticationFeature> _newHttpAuthenticationFeature = f => new HttpAuthenticationFeature();
         private readonly static Func<IFeatureCollection, IHttpRequestLifetimeFeature> _newHttpRequestLifetimeFeature = f => new HttpRequestLifetimeFeature();
         private readonly static Func<IFeatureCollection, ISessionFeature> _newSessionFeature = f => new DefaultSessionFeature();
-        private readonly static Func<IFeatureCollection, ISessionFeature> _nullSessionFeature = f => null;
+        private readonly static Func<IFeatureCollection, ISessionFeature?> _nullSessionFeature = f => null;
         private readonly static Func<IFeatureCollection, IHttpRequestIdentifierFeature> _newHttpRequestIdentifierFeature = f => new HttpRequestIdentifierFeature();
 
         private FeatureReferences<FeatureInterfaces> _features;
@@ -32,8 +33,8 @@ namespace Microsoft.AspNetCore.Http
         private readonly DefaultHttpRequest _request;
         private readonly DefaultHttpResponse _response;
 
-        private DefaultConnectionInfo _connection;
+        private DefaultConnectionInfo? _connection;
-        private DefaultWebSocketManager _websockets;
+        private DefaultWebSocketManager? _websockets;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="DefaultHttpContext"/> class.
@@ -92,7 +93,7 @@ namespace Microsoft.AspNetCore.Http
         /// <returns>
         /// <see cref="FormOptions"/>        
         /// </returns>
-        public FormOptions FormOptions { get; set; }
+        public FormOptions FormOptions { get; set; } = default!;
 
         /// <summary>
         /// Gets or sets the <see cref="IServiceScopeFactory" /> for this instance.
@@ -100,29 +101,28 @@ namespace Microsoft.AspNetCore.Http
         /// <returns>   
         /// <see cref="IServiceScopeFactory"/>      
         /// </returns>
-        public IServiceScopeFactory ServiceScopeFactory { get; set; }
+        public IServiceScopeFactory ServiceScopeFactory { get; set; } = default!;
 
         private IItemsFeature ItemsFeature =>
-            _features.Fetch(ref _features.Cache.Items, _newItemsFeature);
+            _features.Fetch(ref _features.Cache.Items, _newItemsFeature)!;
 
         private IServiceProvidersFeature ServiceProvidersFeature =>
-            _features.Fetch(ref _features.Cache.ServiceProviders, this, _newServiceProvidersFeature);
+            _features.Fetch(ref _features.Cache.ServiceProviders, this, _newServiceProvidersFeature)!;
 
         private IHttpAuthenticationFeature HttpAuthenticationFeature =>
-            _features.Fetch(ref _features.Cache.Authentication, _newHttpAuthenticationFeature);
+            _features.Fetch(ref _features.Cache.Authentication, _newHttpAuthenticationFeature)!;
 
         private IHttpRequestLifetimeFeature LifetimeFeature =>
-            _features.Fetch(ref _features.Cache.Lifetime, _newHttpRequestLifetimeFeature);
+            _features.Fetch(ref _features.Cache.Lifetime, _newHttpRequestLifetimeFeature)!;
 
         private ISessionFeature SessionFeature =>
-            _features.Fetch(ref _features.Cache.Session, _newSessionFeature);
+            _features.Fetch(ref _features.Cache.Session, _newSessionFeature)!;
 
-        private ISessionFeature SessionFeatureOrNull =>
+        private ISessionFeature? SessionFeatureOrNull =>
             _features.Fetch(ref _features.Cache.Session, _nullSessionFeature);
 
-
         private IHttpRequestIdentifierFeature RequestIdentifierFeature =>
-            _features.Fetch(ref _features.Cache.RequestIdentifier, _newHttpRequestIdentifierFeature);
+            _features.Fetch(ref _features.Cache.RequestIdentifier, _newHttpRequestIdentifierFeature)!;
 
         /// <inheritdoc/>
         public override IFeatureCollection Features => _features.Collection ?? ContextDisposed();
@@ -156,7 +156,7 @@ namespace Microsoft.AspNetCore.Http
         }
 
         /// <inheritdoc/>
-        public override IDictionary<object, object> Items
+        public override IDictionary<object, object?> Items
         {
             get { return ItemsFeature.Items; }
             set { ItemsFeature.Items = value; }
@@ -221,6 +221,7 @@ namespace Microsoft.AspNetCore.Http
             return null;
         }
 
+        [DoesNotReturn]
         private static void ThrowContextDisposed()
         {
             throw new ObjectDisposedException(nameof(HttpContext), $"Request has finished and {nameof(HttpContext)} disposed.");
@@ -228,12 +229,12 @@ namespace Microsoft.AspNetCore.Http
 
         struct FeatureInterfaces
         {
-            public IItemsFeature Items;
+            public IItemsFeature? Items;
-            public IServiceProvidersFeature ServiceProviders;
+            public IServiceProvidersFeature? ServiceProviders;
-            public IHttpAuthenticationFeature Authentication;
+            public IHttpAuthenticationFeature? Authentication;
-            public IHttpRequestLifetimeFeature Lifetime;
+            public IHttpRequestLifetimeFeature? Lifetime;
-            public ISessionFeature Session;
+            public ISessionFeature? Session;
-            public IHttpRequestIdentifierFeature RequestIdentifier;
+            public IHttpRequestIdentifierFeature? RequestIdentifier;
         }
     }
 }

src/Http/Http/src/Features/Authentication/HttpAuthenticationFeature.cs

@@ -7,10 +7,6 @@ namespace Microsoft.AspNetCore.Http.Features.Authentication
 {
     public class HttpAuthenticationFeature : IHttpAuthenticationFeature
     {
-        public ClaimsPrincipal User
+        public ClaimsPrincipal? User { get; set; }
-        {
-            get;
-            set;
-        }
     }
 }

src/Http/Http/src/Features/DefaultSessionFeature.cs

@@ -9,6 +9,6 @@ namespace Microsoft.AspNetCore.Http.Features
     /// </summary>
     public class DefaultSessionFeature : ISessionFeature
     {
-        public ISession Session { get; set; }
+        public ISession Session { get; set; } = default!;
     }
 }

src/Http/Http/src/Features/FormFeature.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Text;
 using System.Threading;
@@ -16,8 +17,8 @@ namespace Microsoft.AspNetCore.Http.Features
     {
         private readonly HttpRequest _request;
         private readonly FormOptions _options;
-        private Task<IFormCollection> _parsedFormTask;
+        private Task<IFormCollection>? _parsedFormTask;
-        private IFormCollection _form;
+        private IFormCollection? _form;
 
         public FormFeature(IFormCollection form)
         {
@@ -27,7 +28,10 @@ namespace Microsoft.AspNetCore.Http.Features
             }
 
             Form = form;
+            _request = default!;
+            _options = FormOptions.Default;
         }
+
         public FormFeature(HttpRequest request)
             : this(request, FormOptions.Default)
         {
@@ -48,12 +52,11 @@ namespace Microsoft.AspNetCore.Http.Features
             _options = options;
         }
 
-        private MediaTypeHeaderValue ContentType
+        private MediaTypeHeaderValue? ContentType
         {
             get
             {
-                MediaTypeHeaderValue mt;
+                MediaTypeHeaderValue.TryParse(_request.ContentType, out var mt);
-                MediaTypeHeaderValue.TryParse(_request.ContentType, out mt);
                 return mt;
             }
         }
@@ -73,7 +76,7 @@ namespace Microsoft.AspNetCore.Http.Features
             }
         }
 
-        public IFormCollection Form
+        public IFormCollection? Form
         {
             get { return _form; }
             set
@@ -138,11 +141,11 @@ namespace Microsoft.AspNetCore.Http.Features
                 _request.EnableRewind(_options.MemoryBufferThreshold, _options.BufferBodyLengthLimit);
             }
 
-            FormCollection formFields = null;
+            FormCollection? formFields = null;
-            FormFileCollection files = null;
+            FormFileCollection? files = null;
 
             // Some of these code paths use StreamReader which does not support cancellation tokens.
-            using (cancellationToken.Register((state) => ((HttpContext)state).Abort(), _request.HttpContext))
+            using (cancellationToken.Register((state) => ((HttpContext)state!).Abort(), _request.HttpContext))
             {
                 var contentType = ContentType;
                 // Check the content-type
@@ -270,7 +273,7 @@ namespace Microsoft.AspNetCore.Http.Features
             return Form;
         }
 
-        private Encoding FilterEncoding(Encoding encoding)
+        private static Encoding FilterEncoding(Encoding? encoding)
         {
             // UTF-7 is insecure and should not be honored. UTF-8 will succeed for most cases.
             if (encoding == null || Encoding.UTF7.Equals(encoding))
@@ -280,13 +283,13 @@ namespace Microsoft.AspNetCore.Http.Features
             return encoding;
         }
 
-        private bool HasApplicationFormContentType(MediaTypeHeaderValue contentType)
+        private bool HasApplicationFormContentType([NotNullWhen(true)] MediaTypeHeaderValue? contentType)
         {
             // Content-Type: application/x-www-form-urlencoded; charset=utf-8
             return contentType != null && contentType.MediaType.Equals("application/x-www-form-urlencoded", StringComparison.OrdinalIgnoreCase);
         }
 
-        private bool HasMultipartFormContentType(MediaTypeHeaderValue contentType)
+        private bool HasMultipartFormContentType([NotNullWhen(true)] MediaTypeHeaderValue? contentType)
         {
             // Content-Type: multipart/form-data; boundary=----WebKitFormBoundarymx2fSWqWSd0OxQqq
             return contentType != null && contentType.MediaType.Equals("multipart/form-data", StringComparison.OrdinalIgnoreCase);

src/Http/Http/src/Features/HttpConnectionFeature.cs

@@ -7,14 +7,14 @@ namespace Microsoft.AspNetCore.Http.Features
 {
     public class HttpConnectionFeature : IHttpConnectionFeature
     {
-        public string ConnectionId { get; set; }
+        public string ConnectionId { get; set; } = default!;
 
-        public IPAddress LocalIpAddress { get; set; }
+        public IPAddress? LocalIpAddress { get; set; }
 
         public int LocalPort { get; set; }
 
-        public IPAddress RemoteIpAddress { get; set; }
+        public IPAddress? RemoteIpAddress { get; set; }
 
         public int RemotePort { get; set; }
     }
-}
+}

src/Http/Http/src/Features/HttpRequestIdentifierFeature.cs

@@ -15,7 +15,7 @@ namespace Microsoft.AspNetCore.Http.Features
         // for a roughly increasing _requestId over restarts
         private static long _requestId = DateTime.UtcNow.Ticks;
 
-        private string _id = null;
+        private string? _id = null;
 
         public string TraceIdentifier
         {

src/Http/Http/src/Features/HttpResponseFeature.cs

@@ -18,7 +18,7 @@ namespace Microsoft.AspNetCore.Http.Features
 
         public int StatusCode { get; set; }
 
-        public string ReasonPhrase { get; set; }
+        public string? ReasonPhrase { get; set; }
 
         public IHeaderDictionary Headers { get; set; }
 

src/Http/Http/src/Features/ItemsFeature.cs

@@ -12,6 +12,6 @@ namespace Microsoft.AspNetCore.Http.Features
             Items = new ItemsDictionary();
         }
 
-        public IDictionary<object, object> Items { get; set; }
+        public IDictionary<object, object?> Items { get; set; }
     }
 }

src/Http/Http/src/Features/QueryFeature.cs

@@ -9,12 +9,12 @@ namespace Microsoft.AspNetCore.Http.Features
     public class QueryFeature : IQueryFeature
     {
         // Lambda hoisted to static readonly field to improve inlining https://github.com/dotnet/roslyn/issues/13624
-        private readonly static Func<IFeatureCollection, IHttpRequestFeature> _nullRequestFeature = f => null;
+        private readonly static Func<IFeatureCollection, IHttpRequestFeature?> _nullRequestFeature = f => null;
 
         private FeatureReferences<IHttpRequestFeature> _features;
 
-        private string _original;
+        private string? _original;
-        private IQueryCollection _parsedValues;
+        private IQueryCollection? _parsedValues;
 
         public QueryFeature(IQueryCollection query)
         {
@@ -37,7 +37,7 @@ namespace Microsoft.AspNetCore.Http.Features
         }
 
         private IHttpRequestFeature HttpRequestFeature =>
-            _features.Fetch(ref _features.Cache, _nullRequestFeature);
+            _features.Fetch(ref _features.Cache, _nullRequestFeature)!;
 
         public IQueryCollection Query
         {

src/Http/Http/src/Features/RequestBodyPipeFeature.cs

@@ -10,8 +10,8 @@ namespace Microsoft.AspNetCore.Http.Features
 {
     public class RequestBodyPipeFeature : IRequestBodyPipeFeature
     {
-        private PipeReader _internalPipeReader;
+        private PipeReader? _internalPipeReader;
-        private Stream _streamInstanceWhenWrapped;
+        private Stream? _streamInstanceWhenWrapped;
         private HttpContext _context;
 
         public RequestBodyPipeFeature(HttpContext context)

src/Http/Http/src/Features/RequestCookiesFeature.cs

@@ -11,11 +11,11 @@ namespace Microsoft.AspNetCore.Http.Features
     public class RequestCookiesFeature : IRequestCookiesFeature
     {
         // Lambda hoisted to static readonly field to improve inlining https://github.com/dotnet/roslyn/issues/13624
-        private readonly static Func<IFeatureCollection, IHttpRequestFeature> _nullRequestFeature = f => null;
+        private readonly static Func<IFeatureCollection, IHttpRequestFeature?> _nullRequestFeature = f => null;
 
         private FeatureReferences<IHttpRequestFeature> _features;
         private StringValues _original;
-        private IRequestCookieCollection _parsedValues;
+        private IRequestCookieCollection? _parsedValues;
 
         public RequestCookiesFeature(IRequestCookieCollection cookies)
         {
@@ -38,7 +38,7 @@ namespace Microsoft.AspNetCore.Http.Features
         }
 
         private IHttpRequestFeature HttpRequestFeature =>
-            _features.Fetch(ref _features.Cache, _nullRequestFeature);
+            _features.Fetch(ref _features.Cache, _nullRequestFeature)!;
 
         public IRequestCookieCollection Cookies
         {

src/Http/Http/src/Features/RequestServicesFeature.cs

@@ -9,13 +9,13 @@ namespace Microsoft.AspNetCore.Http.Features
 {
     public class RequestServicesFeature : IServiceProvidersFeature, IDisposable, IAsyncDisposable
     {
-        private readonly IServiceScopeFactory _scopeFactory;
+        private readonly IServiceScopeFactory? _scopeFactory;
-        private IServiceProvider _requestServices;
+        private IServiceProvider? _requestServices;
-        private IServiceScope _scope;
+        private IServiceScope? _scope;
         private bool _requestServicesSet;
         private readonly HttpContext _context;
 
-        public RequestServicesFeature(HttpContext context, IServiceScopeFactory scopeFactory)
+        public RequestServicesFeature(HttpContext context, IServiceScopeFactory? scopeFactory)
         {
             _context = context;
             _scopeFactory = scopeFactory;
@@ -32,7 +32,7 @@ namespace Microsoft.AspNetCore.Http.Features
                     _requestServices = _scope.ServiceProvider;
                     _requestServicesSet = true;
                 }
-                return _requestServices;
+                return _requestServices!;
             }
 
             set

src/Http/Http/src/Features/ResponseCookiesFeature.cs

@@ -13,10 +13,10 @@ namespace Microsoft.AspNetCore.Http.Features
     public class ResponseCookiesFeature : IResponseCookiesFeature
     {
         // Lambda hoisted to static readonly field to improve inlining https://github.com/dotnet/roslyn/issues/13624
-        private readonly static Func<IFeatureCollection, IHttpResponseFeature> _nullResponseFeature = f => null;
+        private readonly static Func<IFeatureCollection, IHttpResponseFeature?> _nullResponseFeature = f => null;
 
         private FeatureReferences<IHttpResponseFeature> _features;
-        private IResponseCookies _cookiesCollection;
+        private IResponseCookies? _cookiesCollection;
 
         /// <summary>
         /// Initializes a new <see cref="ResponseCookiesFeature"/> instance.
@@ -38,7 +38,7 @@ namespace Microsoft.AspNetCore.Http.Features
         /// <see cref="IResponseCookiesFeature"/> and the <see cref="IHttpResponseFeature"/>.
         /// </param>
         /// <param name="builderPool">The <see cref="ObjectPool{T}"/>, if available.</param>
-        public ResponseCookiesFeature(IFeatureCollection features, ObjectPool<StringBuilder> builderPool)
+        public ResponseCookiesFeature(IFeatureCollection features, ObjectPool<StringBuilder>? builderPool)
         {
             if (features == null)
             {
@@ -48,7 +48,7 @@ namespace Microsoft.AspNetCore.Http.Features
             _features.Initalize(features);
         }
 
-        private IHttpResponseFeature HttpResponseFeature => _features.Fetch(ref _features.Cache, _nullResponseFeature);
+        private IHttpResponseFeature HttpResponseFeature => _features.Fetch(ref _features.Cache, _nullResponseFeature)!;
 
         /// <inheritdoc />
         public IResponseCookies Cookies
@@ -58,7 +58,7 @@ namespace Microsoft.AspNetCore.Http.Features
                 if (_cookiesCollection == null)
                 {
                     var headers = HttpResponseFeature.Headers;
-                    _cookiesCollection = new ResponseCookies(headers, null);
+                    _cookiesCollection = new ResponseCookies(headers);
                 }
 
                 return _cookiesCollection;

src/Http/Http/src/Features/RouteValuesFeature.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using Microsoft.AspNetCore.Routing;
@@ -11,7 +11,7 @@ namespace Microsoft.AspNetCore.Http.Features
     /// </summary>
     public class RouteValuesFeature : IRouteValuesFeature
     {
-        private RouteValueDictionary _routeValues;
+        private RouteValueDictionary? _routeValues;
 
         /// <summary>
         /// Gets or sets the <see cref="RouteValueDictionary"/> associated with the currrent
@@ -31,4 +31,4 @@ namespace Microsoft.AspNetCore.Http.Features
             set => _routeValues = value;
         }
     }
-}
+}

src/Http/Http/src/Features/ServiceProvidersFeature.cs

@@ -7,6 +7,6 @@ namespace Microsoft.AspNetCore.Http.Features
 {
     public class ServiceProvidersFeature : IServiceProvidersFeature
     {
-        public IServiceProvider RequestServices { get; set; }
+        public IServiceProvider RequestServices { get; set; } = default!;
     }
-}
+}

src/Http/Http/src/Features/TlsConnectionFeature.cs

@@ -9,11 +9,11 @@ namespace Microsoft.AspNetCore.Http.Features
 {
     public class TlsConnectionFeature : ITlsConnectionFeature
     {
-        public X509Certificate2 ClientCertificate { get; set; }
+        public X509Certificate2? ClientCertificate { get; set; }
 
-        public Task<X509Certificate2> GetClientCertificateAsync(CancellationToken cancellationToken)
+        public Task<X509Certificate2?> GetClientCertificateAsync(CancellationToken cancellationToken)
         {
             return Task.FromResult(ClientCertificate);
         }
     }
-}
+}

src/Http/Http/src/FormCollection.cs

@@ -23,14 +23,14 @@ namespace Microsoft.AspNetCore.Http
 
         private static IFormFileCollection EmptyFiles = new FormFileCollection();
 
-        private IFormFileCollection _files;
+        private IFormFileCollection? _files;
 
         private FormCollection()
         {
             // For static Empty
         }
 
-        public FormCollection(Dictionary<string, StringValues> fields, IFormFileCollection files = null)
+        public FormCollection(Dictionary<string, StringValues>? fields, IFormFileCollection? files = null)
         {
             // can be null
             Store = fields;
@@ -46,7 +46,7 @@ namespace Microsoft.AspNetCore.Http
             private set { _files = value; }
         }
 
-        private Dictionary<string, StringValues> Store { get; set; }
+        private Dictionary<string, StringValues>? Store { get; set; }
 
         /// <summary>
         /// Get or sets the associated value from the collection as a single string.

src/Http/Http/src/FormFile.cs

@@ -50,7 +50,7 @@ namespace Microsoft.AspNetCore.Http
         /// <summary>
         /// Gets the header dictionary of the uploaded file.
         /// </summary>
-        public IHeaderDictionary Headers { get; set; }
+        public IHeaderDictionary Headers { get; set; } = default!;
 
         /// <summary>
         /// Gets the file length in bytes.

src/Http/Http/src/FormFileCollection.cs

@@ -12,10 +12,10 @@ namespace Microsoft.AspNetCore.Http
     public class FormFileCollection : List<IFormFile>, IFormFileCollection
     {
         /// <inheritdoc />
-        public IFormFile this[string name] => GetFile(name);
+        public IFormFile? this[string name] => GetFile(name);
 
         /// <inheritdoc />
-        public IFormFile GetFile(string name)
+        public IFormFile? GetFile(string name)
         {
             foreach (var file in this)
             {

src/Http/Http/src/HeaderDictionary.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.Extensions.Primitives;
 using Microsoft.Net.Http.Headers;
 
@@ -25,7 +26,7 @@ namespace Microsoft.AspNetCore.Http
         {
         }
 
-        public HeaderDictionary(Dictionary<string, StringValues> store)
+        public HeaderDictionary(Dictionary<string, StringValues>? store)
         {
             Store = store;
         }
@@ -35,8 +36,9 @@ namespace Microsoft.AspNetCore.Http
             EnsureStore(capacity);
         }
 
-        private Dictionary<string, StringValues> Store { get; set; }
+        private Dictionary<string, StringValues>? Store { get; set; }
 
+        [MemberNotNull(nameof(Store))]
         private void EnsureStore(int capacity)
         {
             if (Store == null)
@@ -93,7 +95,7 @@ namespace Microsoft.AspNetCore.Http
         /// <returns></returns>
         StringValues IDictionary<string, StringValues>.this[string key]
         {
-            get { return Store[key]; }
+            get { return this[key]; }
             set
             {
                 ThrowIfReadOnly();

src/Http/Http/src/HttpContextAccessor.cs

@@ -13,7 +13,7 @@ namespace Microsoft.AspNetCore.Http
         private static AsyncLocal<HttpContextHolder> _httpContextCurrent = new AsyncLocal<HttpContextHolder>();
 
         /// <inheritdoc/>
-        public HttpContext HttpContext
+        public HttpContext? HttpContext
         {
             get
             {
@@ -39,7 +39,7 @@ namespace Microsoft.AspNetCore.Http
 
         private class HttpContextHolder
         {
-            public HttpContext Context;
+            public HttpContext? Context;
         }
     }
 }

src/Http/Http/src/HttpContextFactory.cs

@@ -14,7 +14,7 @@ namespace Microsoft.AspNetCore.Http
     [Obsolete("This is obsolete and will be removed in a future version. Use DefaultHttpContextFactory instead.")]
     public class HttpContextFactory : IHttpContextFactory
     {
-        private readonly IHttpContextAccessor _httpContextAccessor;
+        private readonly IHttpContextAccessor? _httpContextAccessor;
         private readonly FormOptions _formOptions;
         private readonly IServiceScopeFactory _serviceScopeFactory;
 
@@ -23,7 +23,7 @@ namespace Microsoft.AspNetCore.Http
         /// </summary>
         /// <param name="formOptions">Options to set when instantianting the HTTP context object.</param>
         public HttpContextFactory(IOptions<FormOptions> formOptions)
-            : this(formOptions, serviceScopeFactory: null)
+            : this(formOptions, serviceScopeFactory: null!)
         {
         }
 
@@ -42,8 +42,8 @@ namespace Microsoft.AspNetCore.Http
         /// </summary>
         /// <param name="formOptions">Options to set when instantianting the HTTP context object.</param>
         /// <param name="httpContextAccessor">Object to be used to access the HTTP context instance.</param>
-        public HttpContextFactory(IOptions<FormOptions> formOptions, IHttpContextAccessor httpContextAccessor)
+        public HttpContextFactory(IOptions<FormOptions> formOptions, IHttpContextAccessor? httpContextAccessor)
-            : this(formOptions, serviceScopeFactory: null, httpContextAccessor: httpContextAccessor)
+            : this(formOptions, serviceScopeFactory: null!, httpContextAccessor: httpContextAccessor)
         {
         }
 
@@ -53,7 +53,7 @@ namespace Microsoft.AspNetCore.Http
         /// <param name="formOptions">Options to set when instantianting the HTTP context object.</param>
         /// <param name="serviceScopeFactory">Factory object used to create the service scope for the HTTP context.</param>
         /// <param name="httpContextAccessor">Options to set when instantianting the Default HTTP context object.</param>
-        public HttpContextFactory(IOptions<FormOptions> formOptions, IServiceScopeFactory serviceScopeFactory, IHttpContextAccessor httpContextAccessor)
+        public HttpContextFactory(IOptions<FormOptions> formOptions, IServiceScopeFactory serviceScopeFactory, IHttpContextAccessor? httpContextAccessor)
         {
             if (formOptions == null)
             {

src/Http/Http/src/Internal/DefaultConnectionInfo.cs

@@ -39,10 +39,10 @@ namespace Microsoft.AspNetCore.Http
         }
 
         private IHttpConnectionFeature HttpConnectionFeature =>
-            _features.Fetch(ref _features.Cache.Connection, _newHttpConnectionFeature);
+            _features.Fetch(ref _features.Cache.Connection, _newHttpConnectionFeature)!;
 
         private ITlsConnectionFeature TlsConnectionFeature=>
-            _features.Fetch(ref _features.Cache.TlsConnection, _newTlsConnectionFeature);
+            _features.Fetch(ref _features.Cache.TlsConnection, _newTlsConnectionFeature)!;
 
         /// <inheritdoc />
         public override string Id
@@ -51,7 +51,7 @@ namespace Microsoft.AspNetCore.Http
             set { HttpConnectionFeature.ConnectionId = value; }
         }
 
-        public override IPAddress RemoteIpAddress
+        public override IPAddress? RemoteIpAddress
         {
             get { return HttpConnectionFeature.RemoteIpAddress; }
             set { HttpConnectionFeature.RemoteIpAddress = value; }
@@ -63,7 +63,7 @@ namespace Microsoft.AspNetCore.Http
             set { HttpConnectionFeature.RemotePort = value; }
         }
 
-        public override IPAddress LocalIpAddress
+        public override IPAddress? LocalIpAddress
         {
             get { return HttpConnectionFeature.LocalIpAddress; }
             set { HttpConnectionFeature.LocalIpAddress = value; }
@@ -75,21 +75,21 @@ namespace Microsoft.AspNetCore.Http
             set { HttpConnectionFeature.LocalPort = value; }
         }
 
-        public override X509Certificate2 ClientCertificate
+        public override X509Certificate2? ClientCertificate
         {
             get { return TlsConnectionFeature.ClientCertificate; }
             set { TlsConnectionFeature.ClientCertificate = value; }
         }
 
-        public override Task<X509Certificate2> GetClientCertificateAsync(CancellationToken cancellationToken = default)
+        public override Task<X509Certificate2?> GetClientCertificateAsync(CancellationToken cancellationToken = default)
         {
             return TlsConnectionFeature.GetClientCertificateAsync(cancellationToken);
         }
 
         struct FeatureInterfaces
         {
-            public IHttpConnectionFeature Connection;
+            public IHttpConnectionFeature? Connection;
-            public ITlsConnectionFeature TlsConnection;
+            public ITlsConnectionFeature? TlsConnection;
         }
     }
 }

src/Http/Http/src/Internal/DefaultHttpRequest.cs

@@ -18,8 +18,8 @@ namespace Microsoft.AspNetCore.Http
         private const string Https = "https";
 
         // Lambdas hoisted to static readonly fields to improve inlining https://github.com/dotnet/roslyn/issues/13624
-        private readonly static Func<IFeatureCollection, IHttpRequestFeature> _nullRequestFeature = f => null;
+        private readonly static Func<IFeatureCollection, IHttpRequestFeature?> _nullRequestFeature = f => null;
-        private readonly static Func<IFeatureCollection, IQueryFeature> _newQueryFeature = f => new QueryFeature(f);
+        private readonly static Func<IFeatureCollection, IQueryFeature?> _newQueryFeature = f => new QueryFeature(f);
         private readonly static Func<DefaultHttpRequest, IFormFeature> _newFormFeature = r => new FormFeature(r, r._context.FormOptions ?? FormOptions.Default);
         private readonly static Func<IFeatureCollection, IRequestCookiesFeature> _newRequestCookiesFeature = f => new RequestCookiesFeature(f);
         private readonly static Func<IFeatureCollection, IRouteValuesFeature> _newRouteValuesFeature = f => new RouteValuesFeature();
@@ -52,39 +52,39 @@ namespace Microsoft.AspNetCore.Http
         public override HttpContext HttpContext => _context;
 
         private IHttpRequestFeature HttpRequestFeature =>
-            _features.Fetch(ref _features.Cache.Request, _nullRequestFeature);
+            _features.Fetch(ref _features.Cache.Request, _nullRequestFeature)!;
 
         private IQueryFeature QueryFeature =>
-            _features.Fetch(ref _features.Cache.Query, _newQueryFeature);
+            _features.Fetch(ref _features.Cache.Query, _newQueryFeature)!;
 
         private IFormFeature FormFeature =>
-            _features.Fetch(ref _features.Cache.Form, this, _newFormFeature);
+            _features.Fetch(ref _features.Cache.Form, this, _newFormFeature)!;
 
         private IRequestCookiesFeature RequestCookiesFeature =>
-            _features.Fetch(ref _features.Cache.Cookies, _newRequestCookiesFeature);
+            _features.Fetch(ref _features.Cache.Cookies, _newRequestCookiesFeature)!;
 
         private IRouteValuesFeature RouteValuesFeature =>
-            _features.Fetch(ref _features.Cache.RouteValues, _newRouteValuesFeature);
+            _features.Fetch(ref _features.Cache.RouteValues, _newRouteValuesFeature)!;
 
         private IRequestBodyPipeFeature RequestBodyPipeFeature =>
-            _features.Fetch(ref _features.Cache.BodyPipe, this.HttpContext, _newRequestBodyPipeFeature);
+            _features.Fetch(ref _features.Cache.BodyPipe, this.HttpContext, _newRequestBodyPipeFeature)!;
 
         public override PathString PathBase
         {
             get { return new PathString(HttpRequestFeature.PathBase); }
-            set { HttpRequestFeature.PathBase = value.Value; }
+            set { HttpRequestFeature.PathBase = value.Value ?? string.Empty; }
         }
 
         public override PathString Path
         {
             get { return new PathString(HttpRequestFeature.Path); }
-            set { HttpRequestFeature.Path = value.Value; }
+            set { HttpRequestFeature.Path = value.Value ?? string.Empty; }
         }
 
         public override QueryString QueryString
         {
             get { return new QueryString(HttpRequestFeature.QueryString); }
-            set { HttpRequestFeature.QueryString = value.Value; }
+            set { HttpRequestFeature.QueryString = value.Value ?? string.Empty; }
         }
 
         public override long? ContentLength
@@ -181,12 +181,12 @@ namespace Microsoft.AspNetCore.Http
 
         struct FeatureInterfaces
         {
-            public IHttpRequestFeature Request;
+            public IHttpRequestFeature? Request;
-            public IQueryFeature Query;
+            public IQueryFeature? Query;
-            public IFormFeature Form;
+            public IFormFeature? Form;
-            public IRequestCookiesFeature Cookies;
+            public IRequestCookiesFeature? Cookies;
-            public IRouteValuesFeature RouteValues;
+            public IRouteValuesFeature? RouteValues;
-            public IRequestBodyPipeFeature BodyPipe;
+            public IRequestBodyPipeFeature? BodyPipe;
         }
     }
 }

src/Http/Http/src/Internal/DefaultHttpResponse.cs

@@ -14,9 +14,9 @@ namespace Microsoft.AspNetCore.Http
     internal sealed class DefaultHttpResponse : HttpResponse
     {
         // Lambdas hoisted to static readonly fields to improve inlining https://github.com/dotnet/roslyn/issues/13624
-        private readonly static Func<IFeatureCollection, IHttpResponseFeature> _nullResponseFeature = f => null;
+        private readonly static Func<IFeatureCollection, IHttpResponseFeature?> _nullResponseFeature = f => null;
-        private readonly static Func<IFeatureCollection, IHttpResponseBodyFeature> _nullResponseBodyFeature = f => null;
+        private readonly static Func<IFeatureCollection, IHttpResponseBodyFeature?> _nullResponseBodyFeature = f => null;
-        private readonly static Func<IFeatureCollection, IResponseCookiesFeature> _newResponseCookiesFeature = f => new ResponseCookiesFeature(f);
+        private readonly static Func<IFeatureCollection, IResponseCookiesFeature?> _newResponseCookiesFeature = f => new ResponseCookiesFeature(f);
 
         private readonly DefaultHttpContext _context;
         private FeatureReferences<FeatureInterfaces> _features;
@@ -43,13 +43,13 @@ namespace Microsoft.AspNetCore.Http
         }
 
         private IHttpResponseFeature HttpResponseFeature =>
-            _features.Fetch(ref _features.Cache.Response, _nullResponseFeature);
+            _features.Fetch(ref _features.Cache.Response, _nullResponseFeature)!;
 
         private IHttpResponseBodyFeature HttpResponseBodyFeature =>
-            _features.Fetch(ref _features.Cache.ResponseBody, _nullResponseBodyFeature);
+            _features.Fetch(ref _features.Cache.ResponseBody, _nullResponseBodyFeature)!;
 
         private IResponseCookiesFeature ResponseCookiesFeature =>
-            _features.Fetch(ref _features.Cache.Cookies, _newResponseCookiesFeature);
+            _features.Fetch(ref _features.Cache.Cookies, _newResponseCookiesFeature)!;
 
         public override HttpContext HttpContext { get { return _context; } }
 
@@ -176,9 +176,9 @@ namespace Microsoft.AspNetCore.Http
 
         struct FeatureInterfaces
         {
-            public IHttpResponseFeature Response;
+            public IHttpResponseFeature? Response;
-            public IHttpResponseBodyFeature ResponseBody;
+            public IHttpResponseBodyFeature? ResponseBody;
-            public IResponseCookiesFeature Cookies;
+            public IResponseCookiesFeature? Cookies;
         }
     }
 }

src/Http/Http/src/Internal/DefaultWebSocketManager.cs

@@ -13,8 +13,8 @@ namespace Microsoft.AspNetCore.Http
     internal sealed class DefaultWebSocketManager : WebSocketManager
     {
         // Lambdas hoisted to static readonly fields to improve inlining https://github.com/dotnet/roslyn/issues/13624
-        private readonly static Func<IFeatureCollection, IHttpRequestFeature> _nullRequestFeature = f => null;
+        private readonly static Func<IFeatureCollection, IHttpRequestFeature?> _nullRequestFeature = f => null;
-        private readonly static Func<IFeatureCollection, IHttpWebSocketFeature> _nullWebSocketFeature = f => null;
+        private readonly static Func<IFeatureCollection, IHttpWebSocketFeature?> _nullWebSocketFeature = f => null;
 
         private FeatureReferences<FeatureInterfaces> _features;
 
@@ -39,10 +39,10 @@ namespace Microsoft.AspNetCore.Http
         }
 
         private IHttpRequestFeature HttpRequestFeature =>
-            _features.Fetch(ref _features.Cache.Request, _nullRequestFeature);
+            _features.Fetch(ref _features.Cache.Request, _nullRequestFeature)!;
 
         private IHttpWebSocketFeature WebSocketFeature =>
-            _features.Fetch(ref _features.Cache.WebSockets, _nullWebSocketFeature);
+            _features.Fetch(ref _features.Cache.WebSockets, _nullWebSocketFeature)!;
 
         public override bool IsWebSocketRequest
         {
@@ -60,7 +60,7 @@ namespace Microsoft.AspNetCore.Http
             }
         }
 
-        public override Task<WebSocket> AcceptWebSocketAsync(string subProtocol)
+        public override Task<WebSocket> AcceptWebSocketAsync(string? subProtocol)
         {
             if (WebSocketFeature == null)
             {
@@ -71,8 +71,8 @@ namespace Microsoft.AspNetCore.Http
 
         struct FeatureInterfaces
         {
-            public IHttpRequestFeature Request;
+            public IHttpRequestFeature? Request;
-            public IHttpWebSocketFeature WebSockets;
+            public IHttpWebSocketFeature? WebSockets;
         }
     }
 }

src/Http/Http/src/Internal/ItemsDictionary.cs

@@ -3,25 +3,26 @@
 
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Microsoft.AspNetCore.Http
 {
-    internal class ItemsDictionary : IDictionary<object, object>
+    internal class ItemsDictionary : IDictionary<object, object?>
     {
-        private IDictionary<object, object> _items;
+        private IDictionary<object, object?>? _items;
 
         public ItemsDictionary()
         {}
 
-        public ItemsDictionary(IDictionary<object, object> items)
+        public ItemsDictionary(IDictionary<object, object?> items)
         {
             _items = items;
         }
 
-        public IDictionary<object, object> Items => this;
+        public IDictionary<object, object?> Items => this;
 
         // Replace the indexer with one that returns null for missing values
-        object IDictionary<object, object>.this[object key]
+        object? IDictionary<object, object?>.this[object key]
         {
             get
             {
@@ -38,16 +39,16 @@ namespace Microsoft.AspNetCore.Http
             }
         }
 
-        void IDictionary<object, object>.Add(object key, object value)
+        void IDictionary<object, object?>.Add(object key, object? value)
         {
             EnsureDictionary();
             _items.Add(key, value);
         }
 
-        bool IDictionary<object, object>.ContainsKey(object key)
+        bool IDictionary<object, object?>.ContainsKey(object key)
             => _items != null && _items.ContainsKey(key);
 
-        ICollection<object> IDictionary<object, object>.Keys
+        ICollection<object> IDictionary<object, object?>.Keys
         {
             get
             {
@@ -60,16 +61,16 @@ namespace Microsoft.AspNetCore.Http
             }
         }
 
-        bool IDictionary<object, object>.Remove(object key)
+        bool IDictionary<object, object?>.Remove(object key)
             => _items != null && _items.Remove(key);
 
-        bool IDictionary<object, object>.TryGetValue(object key, out object value)
+        bool IDictionary<object, object?>.TryGetValue(object key, out object? value)
         {
             value = null;
             return _items != null && _items.TryGetValue(key, out value);
         }
 
-        ICollection<object> IDictionary<object, object>.Values
+        ICollection<object?> IDictionary<object, object?>.Values
         {
             get
             {
@@ -82,18 +83,18 @@ namespace Microsoft.AspNetCore.Http
             }
         }
 
-        void ICollection<KeyValuePair<object, object>>.Add(KeyValuePair<object, object> item)
+        void ICollection<KeyValuePair<object, object?>>.Add(KeyValuePair<object, object?> item)
         {
             EnsureDictionary();
             _items.Add(item);
         }
 
-        void ICollection<KeyValuePair<object, object>>.Clear() => _items?.Clear();
+        void ICollection<KeyValuePair<object, object?>>.Clear() => _items?.Clear();
 
-        bool ICollection<KeyValuePair<object, object>>.Contains(KeyValuePair<object, object> item)
+        bool ICollection<KeyValuePair<object, object?>>.Contains(KeyValuePair<object, object?> item)
             => _items != null && _items.Contains(item);
 
-        void ICollection<KeyValuePair<object, object>>.CopyTo(KeyValuePair<object, object>[] array, int arrayIndex)
+        void ICollection<KeyValuePair<object, object?>>.CopyTo(KeyValuePair<object, object?>[] array, int arrayIndex)
         {
             if (_items == null)
             {
@@ -104,11 +105,11 @@ namespace Microsoft.AspNetCore.Http
             _items?.CopyTo(array, arrayIndex);
         }
 
-        int ICollection<KeyValuePair<object, object>>.Count => _items?.Count ?? 0;
+        int ICollection<KeyValuePair<object, object?>>.Count => _items?.Count ?? 0;
 
-        bool ICollection<KeyValuePair<object, object>>.IsReadOnly => _items?.IsReadOnly ?? false;
+        bool ICollection<KeyValuePair<object, object?>>.IsReadOnly => _items?.IsReadOnly ?? false;
 
-        bool ICollection<KeyValuePair<object, object>>.Remove(KeyValuePair<object, object> item)
+        bool ICollection<KeyValuePair<object, object?>>.Remove(KeyValuePair<object, object?> item)
         {
             if (_items == null)
             {
@@ -122,26 +123,27 @@ namespace Microsoft.AspNetCore.Http
             return false;
         }
 
+        [MemberNotNull(nameof(_items))]
         private void EnsureDictionary()
         {
             if (_items == null)
             {
-                _items = new Dictionary<object, object>();
+                _items = new Dictionary<object, object?>();
             }
         }
 
-        IEnumerator<KeyValuePair<object, object>> IEnumerable<KeyValuePair<object, object>>.GetEnumerator()
+        IEnumerator<KeyValuePair<object, object?>> IEnumerable<KeyValuePair<object, object?>>.GetEnumerator()
             => _items?.GetEnumerator() ?? EmptyEnumerator.Instance;
 
         IEnumerator IEnumerable.GetEnumerator() => _items?.GetEnumerator() ?? EmptyEnumerator.Instance;
 
-        private class EmptyEnumerator : IEnumerator<KeyValuePair<object, object>>
+        private class EmptyEnumerator : IEnumerator<KeyValuePair<object, object?>>
         {
             // In own class so only initalized if GetEnumerator is called on an empty ItemsDictionary
-            public readonly static IEnumerator<KeyValuePair<object, object>> Instance = new EmptyEnumerator();
+            public readonly static IEnumerator<KeyValuePair<object, object?>> Instance = new EmptyEnumerator();
-            public KeyValuePair<object, object> Current => default;
+            public KeyValuePair<object, object?> Current => default;
 
-            object IEnumerator.Current => null;
+            object? IEnumerator.Current => null;
 
             public void Dispose()
             { }
@@ -155,8 +157,8 @@ namespace Microsoft.AspNetCore.Http
         private static class EmptyDictionary
         {
             // In own class so only initalized if CopyTo is called on an empty ItemsDictionary
-            public readonly static IDictionary<object, object> Dictionary = new Dictionary<object, object>();
+            public readonly static IDictionary<object, object?> Dictionary = new Dictionary<object, object?>();
-            public static ICollection<KeyValuePair<object, object>> Collection => Dictionary;
+            public static ICollection<KeyValuePair<object, object?>> Collection => Dictionary;
         }
     }
 }

src/Http/Http/src/Internal/RequestCookieCollection.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.Net.Http.Headers;
 
 namespace Microsoft.AspNetCore.Http
@@ -17,7 +18,7 @@ namespace Microsoft.AspNetCore.Http
         private static readonly IEnumerator<KeyValuePair<string, string>> EmptyIEnumeratorType = EmptyEnumerator;
         private static readonly IEnumerator EmptyIEnumerator = EmptyEnumerator;
 
-        private Dictionary<string, string> Store { get; set; }
+        private Dictionary<string, string>? Store { get; set; }
 
         public RequestCookieCollection()
         {
@@ -33,7 +34,7 @@ namespace Microsoft.AspNetCore.Http
             Store = new Dictionary<string, string>(capacity, StringComparer.OrdinalIgnoreCase);
         }
 
-        public string this[string key]
+        public string? this[string key]
         {
             get
             {
@@ -47,8 +48,7 @@ namespace Microsoft.AspNetCore.Http
                     return null;
                 }
 
-                string value;
+                if (TryGetValue(key, out var value))
-                if (TryGetValue(key, out value))
                 {
                     return value;
                 }
@@ -63,8 +63,7 @@ namespace Microsoft.AspNetCore.Http
                 return Empty;
             }
 
-            IList<CookieHeaderValue> cookies;
+            if (CookieHeaderValue.TryParseList(values, out var cookies))
-            if (CookieHeaderValue.TryParseList(values, out cookies))
             {
                 if (cookies.Count == 0)
                 {
@@ -72,7 +71,7 @@ namespace Microsoft.AspNetCore.Http
                 }
 
                 var collection = new RequestCookieCollection(cookies.Count);
-                var store = collection.Store;
+                var store = collection.Store!;
                 for (var i = 0; i < cookies.Count; i++)
                 {
                     var cookie = cookies[i];
@@ -119,7 +118,7 @@ namespace Microsoft.AspNetCore.Http
             return Store.ContainsKey(key);
         }
 
-        public bool TryGetValue(string key, out string value)
+        public bool TryGetValue(string key, [MaybeNullWhen(false)] out string? value)
         {
             if (Store == null)
             {

src/Http/Http/src/Internal/ResponseCookies.cs

@@ -3,8 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Text;
-using Microsoft.Extensions.ObjectPool;
 using Microsoft.Extensions.Primitives;
 using Microsoft.Net.Http.Headers;
 
@@ -19,8 +17,7 @@ namespace Microsoft.AspNetCore.Http
         /// Create a new wrapper.
         /// </summary>
         /// <param name="headers">The <see cref="IHeaderDictionary"/> for the response.</param>
-        /// <param name="builderPool">The <see cref="ObjectPool{T}"/>, if available.</param>
+        public ResponseCookies(IHeaderDictionary headers)
-        public ResponseCookies(IHeaderDictionary headers, ObjectPool<StringBuilder> builderPool)
         {
             if (headers == null)
             {

src/Http/Http/src/Microsoft.AspNetCore.Http.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <Description>ASP.NET Core default HTTP feature implementations.</Description>
@@ -9,6 +9,8 @@
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore</PackageTags>
     <IsPackable>false</IsPackable>
+    <Nullable>enable</Nullable>
+    <LangVersion>preview</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>

src/Http/Http/src/MiddlewareFactory.cs

@@ -1,11 +1,7 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace Microsoft.AspNetCore.Http
@@ -22,7 +18,7 @@ namespace Microsoft.AspNetCore.Http
             _serviceProvider = serviceProvider;
         }
 
-        public IMiddleware Create(Type middlewareType)
+        public IMiddleware? Create(Type middlewareType)
         {
             return _serviceProvider.GetRequiredService(middlewareType) as IMiddleware;
         }

src/Http/Http/src/QueryCollection.cs

@@ -21,7 +21,7 @@ namespace Microsoft.AspNetCore.Http
         private static readonly IEnumerator<KeyValuePair<string, StringValues>> EmptyIEnumeratorType = EmptyEnumerator;
         private static readonly IEnumerator EmptyIEnumerator = EmptyEnumerator;
 
-        private Dictionary<string, StringValues> Store { get; set; }
+        private Dictionary<string, StringValues>? Store { get; set; }
 
         public QueryCollection()
         {

src/Http/Http/src/StreamResponseBodyFeature.cs

@@ -15,7 +15,7 @@ namespace Microsoft.AspNetCore.Http
     /// </summary>
     public class StreamResponseBodyFeature : IHttpResponseBodyFeature
     {
-        private PipeWriter _pipeWriter;
+        private PipeWriter? _pipeWriter;
         private bool _started;
         private bool _completed;
         private bool _disposed;
@@ -48,7 +48,7 @@ namespace Microsoft.AspNetCore.Http
         /// <summary>
         /// The prior feature, if any.
         /// </summary>
-        public IHttpResponseBodyFeature PriorFeature { get; }
+        public IHttpResponseBodyFeature? PriorFeature { get; }
 
         /// <summary>
         /// A PipeWriter adapted over the given stream.

src/Http/Http/test/ResponseCookiesTest.cs

@@ -13,7 +13,7 @@ namespace Microsoft.AspNetCore.Http.Tests
         public void DeleteCookieShouldSetDefaultPath()
         {
             var headers = new HeaderDictionary();
-            var cookies = new ResponseCookies(headers, null);
+            var cookies = new ResponseCookies(headers);
             var testCookie = "TestCookie";
 
             cookies.Delete(testCookie);
@@ -29,7 +29,7 @@ namespace Microsoft.AspNetCore.Http.Tests
         public void DeleteCookieWithCookieOptionsShouldKeepPropertiesOfCookieOptions()
         {
             var headers = new HeaderDictionary();
-            var cookies = new ResponseCookies(headers, null);
+            var cookies = new ResponseCookies(headers);
             var testCookie = "TestCookie";
             var time = new DateTimeOffset(2000, 1, 1, 1, 1, 1, 1, TimeSpan.Zero);
             var options = new CookieOptions
@@ -58,7 +58,7 @@ namespace Microsoft.AspNetCore.Http.Tests
         public void NoParamsDeleteRemovesCookieCreatedByAdd()
         {
             var headers = new HeaderDictionary();
-            var cookies = new ResponseCookies(headers, null);
+            var cookies = new ResponseCookies(headers);
             var testCookie = "TestCookie";
 
             cookies.Append(testCookie, testCookie);
@@ -75,7 +75,7 @@ namespace Microsoft.AspNetCore.Http.Tests
         public void ProvidesMaxAgeWithCookieOptionsArgumentExpectMaxAgeToBeSet()
         {
             var headers = new HeaderDictionary();
-            var cookies = new ResponseCookies(headers, null);
+            var cookies = new ResponseCookies(headers);
             var cookieOptions = new CookieOptions();
             var maxAgeTime = TimeSpan.FromHours(1);
             cookieOptions.MaxAge = TimeSpan.FromHours(1);
@@ -111,7 +111,7 @@ namespace Microsoft.AspNetCore.Http.Tests
             string expected)
         {
             var headers = new HeaderDictionary();
-            var cookies = new ResponseCookies(headers, null);
+            var cookies = new ResponseCookies(headers);
 
             cookies.Append(key, value);
 

src/Http/WebUtilities/ref/Microsoft.AspNetCore.WebUtilities.netcoreapp.cs

@@ -204,7 +204,7 @@ namespace Microsoft.AspNetCore.WebUtilities
     {
         public MultipartSection() { }
         public long? BaseStreamOffset { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
-        public System.IO.Stream? Body { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+        public System.IO.Stream Body { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
         public string? ContentDisposition { get { throw null; } }
         public string? ContentType { get { throw null; } }
         public System.Collections.Generic.Dictionary<string, Microsoft.Extensions.Primitives.StringValues>? Headers { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }

src/Http/WebUtilities/src/MultipartSection.cs

@@ -36,7 +36,10 @@ namespace Microsoft.AspNetCore.WebUtilities
 
         public Dictionary<string, StringValues>? Headers { get; set; }
 
-        public Stream? Body { get; set; }
+        /// <summary>
+        /// Gets or sets the body.
+        /// </summary>
+        public Stream Body { get; set; } = default!;
 
         /// <summary>
         /// The position where the body starts in the total multipart body.

src/Shared/CopyOnWriteDictionary/CopyOnWriteDictionary.cs

@@ -1,17 +1,19 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+#nullable enable
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Microsoft.Extensions.Internal
 {
-    internal class CopyOnWriteDictionary<TKey, TValue> : IDictionary<TKey, TValue>
+    internal class CopyOnWriteDictionary<TKey, TValue> : IDictionary<TKey, TValue> where TKey : notnull
     {
         private readonly IDictionary<TKey, TValue> _sourceDictionary;
         private readonly IEqualityComparer<TKey> _comparer;
-        private IDictionary<TKey, TValue> _innerDictionary;
+        private IDictionary<TKey, TValue>? _innerDictionary;
 
         public CopyOnWriteDictionary(
             IDictionary<TKey, TValue> sourceDictionary,
@@ -112,7 +114,7 @@ namespace Microsoft.Extensions.Internal
             return WriteDictionary.Remove(key);
         }
 
-        public virtual bool TryGetValue(TKey key, out TValue value)
+        public virtual bool TryGetValue(TKey key, [MaybeNullWhen(false)] out TValue value)
         {
             return ReadDictionary.TryGetValue(key, out value);
         }
@@ -152,4 +154,4 @@ namespace Microsoft.Extensions.Internal
             return GetEnumerator();
         }
     }
-}
+}

src/Shared/CopyOnWriteDictionary/CopyOnWriteDictionaryHolder.cs

@@ -1,15 +1,18 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Microsoft.Extensions.Internal
 {
-    internal struct CopyOnWriteDictionaryHolder<TKey, TValue>
+    internal struct CopyOnWriteDictionaryHolder<TKey, TValue> where TKey : notnull
     {
         private readonly Dictionary<TKey, TValue> _source;
-        private Dictionary<TKey, TValue> _copy;
+        private Dictionary<TKey, TValue>? _copy;
 
         public CopyOnWriteDictionaryHolder(Dictionary<TKey, TValue> source)
         {
@@ -128,7 +131,7 @@ namespace Microsoft.Extensions.Internal
             return WriteDictionary.Remove(key);
         }
 
-        public bool TryGetValue(TKey key, out TValue value)
+        public bool TryGetValue(TKey key, [MaybeNullWhen(false)] out TValue value)
         {
             return ReadDictionary.TryGetValue(key, out value);
         }