More thorough support for retrieving OpenAPI routes in a case-sensitive manner

src/OpenApi/src/Extensions/OpenApiEndpointRouteBuilderExtensions.cs

@@ -50,7 +50,7 @@ public static IEndpointConventionBuilder MapOpenApi(this IEndpointRouteBuilder e
                 else
                 {
                     var document = await documentService.GetOpenApiDocumentAsync(context.RequestServices, context.RequestAborted);
-                    var documentOptions = options.Get(documentName);
+                    var documentOptions = options.Get(lowercasedDocumentName);
                     using var output = MemoryBufferWriter.Get();
                     using var writer = Utf8BufferTextWriter.Get(output);
                     try