[c#] Getting absolute URLs using ASP.NET Core

This is a variation of the anwser by Muhammad Rehan Saeed, with the class getting parasitically attached to the existing .net core MVC class of the same name, so that everything just works.

namespace Microsoft.AspNetCore.Mvc
{
    /// <summary>
    /// <see cref="IUrlHelper"/> extension methods.
    /// </summary>
    public static partial class UrlHelperExtensions
    {
        /// <summary>
        /// Generates a fully qualified URL to an action method by using the specified action name, controller name and
        /// route values.
        /// </summary>
        /// <param name="url">The URL helper.</param>
        /// <param name="actionName">The name of the action method.</param>
        /// <param name="controllerName">The name of the controller.</param>
        /// <param name="routeValues">The route values.</param>
        /// <returns>The absolute URL.</returns>
        public static string AbsoluteAction(
            this IUrlHelper url,
            string actionName,
            string controllerName,
            object routeValues = null)
        {
            return url.Action(actionName, controllerName, routeValues, url.ActionContext.HttpContext.Request.Scheme);
        }

        /// <summary>
        /// Generates a fully qualified URL to the specified content by using the specified content path. Converts a
        /// virtual (relative) path to an application absolute path.
        /// </summary>
        /// <param name="url">The URL helper.</param>
        /// <param name="contentPath">The content path.</param>
        /// <returns>The absolute URL.</returns>
        public static string AbsoluteContent(
            this IUrlHelper url,
            string contentPath)
        {
            HttpRequest request = url.ActionContext.HttpContext.Request;
            return new Uri(new Uri(request.Scheme + "://" + request.Host.Value), url.Content(contentPath)).ToString();
        }

        /// <summary>
        /// Generates a fully qualified URL to the specified route by using the route name and route values.
        /// </summary>
        /// <param name="url">The URL helper.</param>
        /// <param name="routeName">Name of the route.</param>
        /// <param name="routeValues">The route values.</param>
        /// <returns>The absolute URL.</returns>
        public static string AbsoluteRouteUrl(
            this IUrlHelper url,
            string routeName,
            object routeValues = null)
        {
            return url.RouteUrl(routeName, routeValues, url.ActionContext.HttpContext.Request.Scheme);
        }
    }
}