为什么我的自定义Razor扩展无法正确生成属性？

我看到很多问题都在这个问题的边缘徘徊，但不尽相同。我在下面编写了简单的HtmlHelper扩展方法，以创建固定文本为的锚链接。同样，编译器太聪明了，不利于自身：

htmlHelper.ActionLink有两个类似的重载：

这导致它改用RouteValueDictionary routeValues，IDictionary HtmlatAttributes方法

<a href="controller/action/id?etc" target="_back">&lt;</a> 

<a Count="1" Keys="System.Collections.Generic.Dictionary`2+KeyCollection[System.String,System.Object]" Values="System.Collections.Generic.Dictionary`2+ValueCollection[System.String,System.Object]" href="controller/action/id?etc">&lt;</a>"

    public static MvcHtmlString BackLink(this HtmlHelper htmlHelper, string actionName, string controller = null, object routeValuesObject = null, object htmlAttributes = null)
    {
        RouteValueDictionary rvd = HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);
        rvd.Add("target", "_back");
        return htmlHelper.ActionLink("<", actionName, controller, routeValuesObject, rvd);
    }

    public static MvcHtmlString ActionLink(this HtmlHelper htmlHelper, string linkText, string actionName, string controllerName, 
           object routeValues, object htmlAttributes);
    public static MvcHtmlString ActionLink(this HtmlHelper htmlHelper, string linkText, string actionName, string controllerName, 
           RouteValueDictionary routeValues, IDictionary<string, object> htmlAttributes);

    public static MvcHtmlString BackLink(this HtmlHelper htmlHelper, string actionName, string controller = null, object routeValuesObject = null, object htmlAttributes = null)
    {
        RouteValueDictionary routeValues = new RouteValueDictionary(routeValuesObject);
        RouteValueDictionary htmlAttr = HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);
        htmlAttr.Add("target", "_back");
        return htmlHelper.ActionLink("<", actionName, controller, routeValues, htmlAttr);
    }