Implemented PR comments

Author: sander1095

src/OpenApi/src/Extensions/OpenApiServiceCollectionExtensions.cs

@@ -105,9 +105,6 @@ public static IServiceCollection AddOpenApi(this IServiceCollection services, Ac
     public static IServiceCollection AddOpenApi(this IServiceCollection services)
         => services.AddOpenApi(OpenApiConstants.DefaultDocumentName);
 
-    /// <param name="services">The <see cref="IServiceCollection"/> to register services onto.</param>
-    /// <param name="documentName">Please ensure this is lowercased to prevent case-sensitive routing issues</param>
-    /// <remarks>See https://github.com/dotnet/aspnetcore/issues/59175 for more information around the routing issue mentioned above</remarks>
     private static IServiceCollection AddOpenApiCore(this IServiceCollection services, string documentName)
     {
         services.AddEndpointsApiExplorer();

src/OpenApi/src/Services/OpenApiDocumentProvider.cs

@@ -25,11 +25,7 @@ internal sealed class OpenApiDocumentProvider(IServiceProvider serviceProvider)
     /// <param name="writer">A text writer associated with the document to write to.</param>
     public async Task GenerateAsync(string documentName, TextWriter writer)
     {
-        // We need to retrieve the document name in a case-insensitive manner to support case-insensitive document name resolution.
-        // The options are registered with a key equal to the document name, but in lowercase.
-        // The options monitor's Get() method is case-sensitive, which doesn't work well for OpenAPI document names here,
-        // as the document name is also used as the route to retrieve the document, so we need to ensure this is lowercased to achieve consistency with ASP.NET Core routing.
-        // See OpenApiServiceCollectionExtensions.cs for more info.
+        // See OpenApiServiceCollectionExtensions.cs to learn why we lowercase the document name
         var lowercasedDocumentName = documentName.ToLowerInvariant();
 
         var options = serviceProvider.GetRequiredService<IOptionsMonitor<OpenApiOptions>>();

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiDocumentProviderTests.cs

@@ -70,6 +70,7 @@ public async Task GenerateAsync_ShouldRetrieveOpenApiDocumentServiceWithACaseIns
         await documentProvider.GenerateAsync(documentName, stringWriter, OpenApiSpecVersion.OpenApi3_0);
 
         // Assert
+        var document = stringWriter.ToString();
 
         // If the Document Service is retrieved with a non-existent (case-sensitive) key, it would throw:
         // https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.dependencyinjection.serviceproviderkeyedserviceextensions.getrequiredkeyedservice?view=net-9.0-pp
@@ -79,6 +80,7 @@ public async Task GenerateAsync_ShouldRetrieveOpenApiDocumentServiceWithACaseIns
         // Therefore, if the test doesn't throw, we know it has passed correctly.
         // We still do a small check to validate the document, just in case. But the main test is that it doesn't throw.
         ValidateOpenApiDocument(stringWriter, _ => { });
+        Assert.StartsWith("{\n  \"openapi\": \"3.0.1\"", document);
     }
 
     [Fact]