Add custom comparer

Add custom comparer for endpoints by their HTTP method.

Author: martincostello

src/Http/Http.Extensions/gen/RequestDelegateGenerator.cs

@@ -175,6 +175,7 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
             .Select((endpoints, _) =>
             {
                 return endpoints
+                    .Distinct(EndpointHttpMethodComparer.Instance)
                     .Select(endpoint => endpoint.EmitterContext.HttpMethod!)
                     .Where(verb => verb is not null)
                     .ToImmutableHashSet();

src/Http/Http.Extensions/gen/StaticRouteHandlerModel/EndpointHttpMethodComparer.cs

@@ -0,0 +1,17 @@
+// 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 System.Collections.Generic;
+
+namespace Microsoft.AspNetCore.Http.RequestDelegateGenerator.StaticRouteHandlerModel;
+
+internal sealed class EndpointHttpMethodComparer : IEqualityComparer<Endpoint>
+{
+    public static readonly EndpointHttpMethodComparer Instance = new();
+    private static readonly IEqualityComparer<string> OrdinalComparer = StringComparer.Ordinal;
+
+    public bool Equals(Endpoint x, Endpoint y) => OrdinalComparer.Equals(x.HttpMethod, y.HttpMethod);
+
+    public int GetHashCode(Endpoint obj) => OrdinalComparer.GetHashCode(obj.HttpMethod);
+}