Support setting endpoints on group names to resolve #34541

Author: captainsafia

src/Http/Routing/src/Builder/RoutingEndpointConventionBuilderExtensions.cs

@@ -131,5 +131,18 @@ public static TBuilder WithName<TBuilder>(this TBuilder builder, string endpoint
             builder.WithMetadata(new EndpointNameMetadata(endpointName));
             return builder;
         }
+
+        /// <summary>
+        /// Sets the <see cref="EndpointGroupNameMetadata"/> for all endpoints produced
+        /// on the target <see cref="IEndpointConventionBuilder"/>.
+        /// </summary>
+        /// <param name="builder">The <see cref="IEndpointConventionBuilder"/>.</param>
+        /// <param name="endpointGroupName">The endpoint group name.</param>
+        /// <returns>The <see cref="IEndpointConventionBuilder"/>.</returns>
+        public static TBuilder WithGroupName<TBuilder>(this TBuilder builder, string endpointGroupName) where TBuilder : IEndpointConventionBuilder
+        {
+            builder.WithMetadata(new EndpointGroupNameMetadata(endpointGroupName));
+            return builder;
+        }
     }
 }

src/Http/Routing/src/EndpointGroupNameMetadata.cs

@@ -0,0 +1,33 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Routing
+{
+    /// <summary>
+    /// Specifies an endpoint group name in <see cref="Endpoint.Metadata"/>.
+    /// </summary>
+    public class EndpointGroupNameMetadata : IEndpointGroupNameMetadata
+    {
+        /// <summary>
+        /// Creates a new instance of <see cref="EndpointGroupNameMetadata"/> with the provided endpoint name.
+        /// </summary>
+        /// <param name="endpointGroupName">The endpoint name.</param>
+        public EndpointGroupNameMetadata(string endpointGroupName)
+        {
+            if (endpointGroupName == null)
+            {
+                throw new ArgumentNullException(nameof(endpointGroupName));
+            }
+
+            EndpointGroupName = endpointGroupName;
+        }
+
+        /// <summary>
+        /// Gets the endpoint name.
+        /// </summary>
+        public string EndpointGroupName { get; }
+    }
+}

src/Http/Routing/src/IEndpointGroupNameMetadata.cs

@@ -0,0 +1,18 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.Routing
+{
+    /// <summary>
+    /// Defines a contract use to specify an endpoint group name in <see cref="Endpoint.Metadata"/>.
+    /// </summary>
+    public interface IEndpointGroupNameMetadata
+    {
+        /// <summary>
+        /// Gets the endpoint group name.
+        /// </summary>
+        string EndpointGroupName { get; }
+    }
+}