protected virtual ITagHelperProvider GetTagHelperProvider(IDependencyResolver resolver, ControllerContext controllerContext)
        {
            var helperContainer = new ActionTagHelperContainer(resolver, controllerContext);
            foreach (var kvp in GetTagHandlers())
                helperContainer.Register(kvp.Key, kvp.Value);

            if (_customTagHandlers != null)
            {
                foreach (var kvp in _customTagHandlers)
                    helperContainer.Register(kvp.Key, kvp.Value);
            }

            return helperContainer;
        }