Make IApiBehaviorMetadata public (#8410)

Fixes #8403

The analyzer expects the type to be present. However since it's listed
as internal, it is not present when compiling against the ref assembly \ targeting pack.

It was left as internal so we could evolve it later, but we haven't found a need for it as yet.

Author: pranavkm

src/Mvc/Mvc.Analyzers/src/SymbolNames.cs

@@ -29,7 +29,7 @@ internal static class SymbolNames
 
         public const string HtmlHelperPartialExtensionsType = "Microsoft.AspNetCore.Mvc.Rendering.HtmlHelperPartialExtensions";
 
-        public const string IApiBehaviorMetadata = "Microsoft.AspNetCore.Mvc.IApiBehaviorMetadata";
+        public const string IApiBehaviorMetadata = "Microsoft.AspNetCore.Mvc.Infrastructure.IApiBehaviorMetadata";
 
         public const string IBinderTypeProviderMetadata = "Microsoft.AspNetCore.Mvc.ModelBinding.IBinderTypeProviderMetadata";
 

src/Mvc/Mvc.Api.Analyzers/src/ApiSymbolNames.cs

@@ -23,7 +23,7 @@ internal static class ApiSymbolNames
 
         public const string DefaultStatusCodeAttribute = "Microsoft.AspNetCore.Mvc.Infrastructure.DefaultStatusCodeAttribute";
 
-        public const string IApiBehaviorMetadata = "Microsoft.AspNetCore.Mvc.IApiBehaviorMetadata";
+        public const string IApiBehaviorMetadata = "Microsoft.AspNetCore.Mvc.Infrastructure.IApiBehaviorMetadata";
 
         public const string IActionResult = "Microsoft.AspNetCore.Mvc.IActionResult";
 

src/Mvc/Mvc.Core/ref/Microsoft.AspNetCore.Mvc.Core.netcoreapp3.0.cs

@@ -115,7 +115,7 @@ public ApiBehaviorOptions() { }
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { throw null; }
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Assembly | System.AttributeTargets.Class, AllowMultiple=false, Inherited=true)]
-    public partial class ApiControllerAttribute : Microsoft.AspNetCore.Mvc.ControllerAttribute, Microsoft.AspNetCore.Mvc.Filters.IFilterMetadata
+    public partial class ApiControllerAttribute : Microsoft.AspNetCore.Mvc.ControllerAttribute, Microsoft.AspNetCore.Mvc.Filters.IFilterMetadata, Microsoft.AspNetCore.Mvc.Infrastructure.IApiBehaviorMetadata
     {
         public ApiControllerAttribute() { }
     }
@@ -1980,6 +1980,9 @@ public partial interface IActionSelector
         Microsoft.AspNetCore.Mvc.Abstractions.ActionDescriptor SelectBestCandidate(Microsoft.AspNetCore.Routing.RouteContext context, System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Mvc.Abstractions.ActionDescriptor> candidates);
         System.Collections.Generic.IReadOnlyList<Microsoft.AspNetCore.Mvc.Abstractions.ActionDescriptor> SelectCandidates(Microsoft.AspNetCore.Routing.RouteContext context);
     }
+    public partial interface IApiBehaviorMetadata : Microsoft.AspNetCore.Mvc.Filters.IFilterMetadata
+    {
+    }
     public partial interface IClientErrorActionResult : Microsoft.AspNetCore.Mvc.IActionResult, Microsoft.AspNetCore.Mvc.Infrastructure.IStatusCodeActionResult
     {
     }

src/Mvc/Mvc.Core/src/ApiControllerAttribute.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 Microsoft.AspNetCore.Mvc.Infrastructure;
 
 namespace Microsoft.AspNetCore.Mvc
 {

src/Mvc/Mvc.Core/src/IApiBehaviorMetadata.cs

@@ -0,0 +1,18 @@
+// 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.Mvc.Filters;
+
+namespace Microsoft.AspNetCore.Mvc.Infrastructure
+{
+    /// <summary>
+    /// A <see cref="IFilterMetadata"/> that indicates that a type and all derived types are used to serve HTTP API responses.
+    /// <para>
+    /// Controllers decorated with this attribute (<see cref="ApiControllerAttribute"/>) are configured with
+    /// features and behavior targeted at improving the developer experience for building APIs.
+    /// </para>
+    /// </summary>
+    public interface IApiBehaviorMetadata : IFilterMetadata
+    {
+    }
+}