Add docs for Microsoft.AspNetCore.Http (#28867)

* Microsoft.AspNetCore.Http
* Microsoft.AspNetCore.Http.Extensions
* Microsoft.AspNetCore.Http.Features

Author: pranavkm

src/Http/Http.Extensions/src/HeaderDictionaryTypeExtensions.cs

@@ -12,13 +12,27 @@
 
 namespace Microsoft.AspNetCore.Http
 {
+    /// <summary>
+    /// Extension methods for accessing strongly typed HTTP request and response
+    /// headers.
+    /// </summary>
     public static class HeaderDictionaryTypeExtensions
     {
+        /// <summary>
+        /// Gets strongly typed HTTP request headers.
+        /// </summary>
+        /// <param name="request">The <see cref="HttpRequest"/>.</param>
+        /// <returns>The <see cref="RequestHeaders"/>.</returns>
         public static RequestHeaders GetTypedHeaders(this HttpRequest request)
         {
             return new RequestHeaders(request.Headers);
         }
 
+        /// <summary>
+        /// Gets strongly typed HTTP response headers.
+        /// </summary>
+        /// <param name="response">The <see cref="HttpResponse"/>.</param>
+        /// <returns>The <see cref="ResponseHeaders"/>.</returns>
         public static ResponseHeaders GetTypedHeaders(this HttpResponse response)
         {
             return new ResponseHeaders(response.Headers);
@@ -94,6 +108,13 @@ internal static void SetList<T>(this IHeaderDictionary headers, string name, ILi
             }
         }
 
+        /// <summary>
+        /// Appends a sequence of values to <see cref="IHeaderDictionary"/>.
+        /// </summary>
+        /// <typeparam name="T">The type of header value.</typeparam>
+        /// <param name="Headers">The <see cref="IHeaderDictionary"/>.</param>
+        /// <param name="name">The header name.</param>
+        /// <param name="values">The values to append.</param>
         public static void AppendList<T>(this IHeaderDictionary Headers, string name, IList<T> values)
         {
             if (name == null)
@@ -246,7 +267,7 @@ internal static IList<T> GetList<T>(this IHeaderDictionary headers, string name)
             var success = (bool)method.Invoke(null, parameters)!;
             if (success)
             {
-                return (T)parameters[1];
+                return (T?)parameters[1];
             }
             return default(T);
         }

src/Http/Http.Extensions/src/HttpContextServerVariableExtensions.cs

@@ -5,6 +5,9 @@
 
 namespace Microsoft.AspNetCore.Http
 {
+    /// <summary>
+    /// Extensions for reading HTTP server variables.
+    /// </summary>
     public static class HttpContextServerVariableExtensions
     {
         /// <summary>

src/Http/Http.Extensions/src/HttpRequestJsonExtensions.cs

@@ -14,10 +14,11 @@
 using Microsoft.Extensions.Primitives;
 using Microsoft.Net.Http.Headers;
 
-#nullable enable
-
 namespace Microsoft.AspNetCore.Http
 {
+    /// <summary>
+    /// Extension methods to read the request body as JSON.
+    /// </summary>
     public static class HttpRequestJsonExtensions
     {
         /// <summary>

src/Http/Http.Extensions/src/HttpRequestMultipartExtensions.cs

@@ -6,8 +6,16 @@
 
 namespace Microsoft.AspNetCore.Http.Extensions
 {
+    /// <summary>
+    /// Extension methods for working with multipart form requests.
+    /// </summary>
     public static class HttpRequestMultipartExtensions
     {
+        /// <summary>
+        /// Gets the mutipart boundary from the <c>Content-Type</c> header.
+        /// </summary>
+        /// <param name="request">The <see cref="HttpRequest"/>.</param>
+        /// <returns>The multipart boundary.</returns>
         public static string GetMultipartBoundary(this HttpRequest request)
         {
             if (request == null)

src/Http/Http.Extensions/src/HttpResponseJsonExtensions.cs

@@ -10,10 +10,11 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 
-#nullable enable
-
 namespace Microsoft.AspNetCore.Http
 {
+    /// <summary>
+    /// Provides extension methods for writing a JSON serialized value to the HTTP response.
+    /// </summary>
     public static partial class HttpResponseJsonExtensions
     {
         /// <summary>

src/Http/Http.Extensions/src/JsonOptions.cs

@@ -8,6 +8,10 @@
 
 namespace Microsoft.AspNetCore.Http.Json
 {
+    /// <summary>
+    /// Options to configure JSON serialization settings for <see cref="HttpRequestJsonExtensions"/>
+    /// and <see cref="HttpResponseJsonExtensions"/>.
+    /// </summary>
     public class JsonOptions
     {
         internal static readonly JsonSerializerOptions DefaultSerializerOptions = new JsonSerializerOptions(JsonSerializerDefaults.Web)
@@ -20,6 +24,9 @@ public class JsonOptions
         };
 
         // Use a copy so the defaults are not modified.
+        /// <summary>
+        /// Gets the <see cref="JsonSerializerOptions"/>.
+        /// </summary>
         public JsonSerializerOptions SerializerOptions { get; } = new JsonSerializerOptions(DefaultSerializerOptions);
     }
 }

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

@@ -4,7 +4,6 @@
     <Description>ASP.NET Core common extension methods for HTTP abstractions, HTTP headers, HTTP request/response, and session state.</Description>
     <TargetFramework>$(DefaultNetCoreTargetFramework)</TargetFramework>
     <IsAspNetCoreApp>true</IsAspNetCoreApp>
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <PackageTags>aspnetcore</PackageTags>
     <IsPackable>false</IsPackable>

src/Http/Http.Extensions/src/QueryBuilder.cs

@@ -11,26 +11,45 @@
 namespace Microsoft.AspNetCore.Http.Extensions
 {
     // The IEnumerable interface is required for the collection initialization syntax: new QueryBuilder() { { "key", "value" } };
+    /// <summary>
+    /// Allows constructing a query string.
+    /// </summary>
     public class QueryBuilder : IEnumerable<KeyValuePair<string, string>>
     {
         private IList<KeyValuePair<string, string>> _params;
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="QueryBuilder"/>.
+        /// </summary>
         public QueryBuilder()
         {
             _params = new List<KeyValuePair<string, string>>();
         }
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="QueryBuilder"/>.
+        /// </summary>
+        /// <param name="parameters">The parameters to initialize the instance with.</param>
         public QueryBuilder(IEnumerable<KeyValuePair<string, string>> parameters)
         {
             _params = new List<KeyValuePair<string, string>>(parameters);
         }
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="QueryBuilder"/>.
+        /// </summary>
+        /// <param name="parameters">The parameters to initialize the instance with.</param>
         public QueryBuilder(IEnumerable<KeyValuePair<string, StringValues>> parameters)
             : this(parameters.SelectMany(kvp => kvp.Value, (kvp, v) => KeyValuePair.Create(kvp.Key, v)))
         {
 
         }
 
+        /// <summary>
+        /// Adds a query string token to the instance.
+        /// </summary>
+        /// <param name="key">The query key.</param>
+        /// <param name="values">The sequence of query values.</param>
         public void Add(string key, IEnumerable<string> values)
         {
             foreach (var value in values)
@@ -39,43 +58,56 @@ public void Add(string key, IEnumerable<string> values)
             }
         }
 
+        /// <summary>
+        /// Adds a query string token to the instance.
+        /// </summary>
+        /// <param name="key">The query key.</param>
+        /// <param name="value">The query value.</param>
         public void Add(string key, string value)
         {
             _params.Add(new KeyValuePair<string, string>(key, value));
         }
 
+        /// <inheritdoc/>
         public override string ToString()
         {
             var builder = new StringBuilder();
             bool first = true;
-            for (int i = 0; i < _params.Count; i++)
+            for (var i = 0; i < _params.Count; i++)
             {
                 var pair = _params[i];
-                builder.Append(first ? "?" : "&");
+                builder.Append(first ? '?' : '&');
                 first = false;
                 builder.Append(UrlEncoder.Default.Encode(pair.Key));
-                builder.Append("=");
+                builder.Append('=');
                 builder.Append(UrlEncoder.Default.Encode(pair.Value));
             }
 
             return builder.ToString();
         }
 
+        /// <summary>
+        /// Constructs a <see cref="QueryString"/> from this <see cref="QueryBuilder"/>.
+        /// </summary>
+        /// <returns>The <see cref="QueryString"/>.</returns>
         public QueryString ToQueryString()
         {
             return new QueryString(ToString());
         }
 
+        /// <inheritdoc/>
         public override int GetHashCode()
         {
             return ToQueryString().GetHashCode();
         }
 
+        /// <inheritdoc/>
         public override bool Equals(object? obj)
         {
             return ToQueryString().Equals(obj);
         }
 
+        /// <inheritdoc/>
         public IEnumerator<KeyValuePair<string, string>> GetEnumerator()
         {
             return _params.GetEnumerator();