ASP.NET Core WebAPI ODATA - Add Custom Metadata Annotation to Feed

CustomSerializer.cs

public class CustomSerializerProvider : DefaultODataSerializerProvider
    {
        public CustomSerializerProvider(IServiceProvider rootContainer)
            : base(rootContainer)
        {
        }
        public override ODataEdmTypeSerializer GetEdmTypeSerializer(IEdmTypeReference edmType)
        {
            if (edmType.IsCollection() && edmType.AsCollection().ElementType().IsEntity())
            {
                return new CustomFeedSerializer(this);
            }
            else if (edmType.IsEntity())
            {
                return new CustomEntrySerializer(this);
            }
            return base.GetEdmTypeSerializer(edmType);
        }
    }
    public class CustomFeedSerializer : ODataResourceSetSerializer
    {
        public CustomFeedSerializer(ODataSerializerProvider serializerProvider)
            : base(serializerProvider)
        {
        }
        public override ODataResourceSet CreateResourceSet(IEnumerable feedInstance, IEdmCollectionTypeReference feedType,
            ODataSerializerContext writeContext)
        {
            try
            {
                ODataResourceSet feed = base.CreateResourceSet(feedInstance, feedType, writeContext);
                Extensions.AddInstanceAnnotationsFromHeader(feed, writeContext.Request);
                return feed;
            } catch
            {
                return base.CreateResourceSet(feedInstance, feedType, writeContext);
            }
        }
    }
    public class CustomEntrySerializer : ODataResourceSerializer
    {
        public CustomEntrySerializer(ODataSerializerProvider serializerProvider)
            : base(serializerProvider)
        {
        }
        public override ODataResource CreateResource(SelectExpandNode selectExpandNode, ResourceContext entityContext)
        {
            ODataResource entry = base.CreateResource(selectExpandNode, entityContext);
            Extensions.AddInstanceAnnotationsFromHeader(entry, entityContext.Request);
            return entry;
        }
    }
    public static class Extensions
    {
        public static void AddInstanceAnnotationsFromHeader(ODataItem resource, Microsoft.AspNetCore.Http.HttpRequest request)
        {
            var prefix = "odataAnnotation_";
            foreach (var header in request.HttpContext.Response.Headers.Where(x => x.Key.StartsWith(prefix)))
            {
                var key = header.Key.Substring(prefix.Length);
                var value = new ODataPrimitiveValue(header.Value.FirstOrDefault());
                var annotation = new ODataInstanceAnnotation(key, value);
                if ((resource as ODataResourceBase) != null)
                {
                    (resource as ODataResourceBase)?.InstanceAnnotations.Add(annotation);
                }
                if ((resource as ODataResourceSetBase) != null)
                {
                    (resource as ODataResourceSetBase)?.InstanceAnnotations.Add(annotation);
                }
            }
        }
    }

Startup.cs

//...
routeBuilder.MapODataServiceRoute("odata", "odata", builder => builder
                            .AddService(Microsoft.OData.ServiceLifetime.Singleton, sp => this.funcEdmModel())
                            .AddService<ODataSerializerProvider, CustomSerializerProvider>(Microsoft.OData.ServiceLifetime.Singleton)   
                            .AddService<IEnumerable<IODataRoutingConvention>>(Microsoft.OData.ServiceLifetime.Singleton, sp =>
                                ODataRoutingConventions.CreateDefaultWithAttributeRouting("odata", routeBuilder))
                        );
//...