How HtmlHelper.AnonymousObjectToHtmlAttributes works behind the scenes? (Method calls itself)

I did a reflection with ILSpy of System.Web.MVC.dll and found out the following code:

public static RouteValueDictionary AnonymousObjectToHtmlAttributes(object htmlAttributes)
    {
        return HtmlHelper.AnonymousObjectToHtmlAttributes(htmlAttributes);
    }

Can someone help me to understand what exactly is happening here? This should lead to a StackOverflow Exception, but doesn't.