UWP MapRouteFinder抛出错误

Question

我正在尝试使用UWP MapControl，但特别是MapRouteFinder。 我已经尝试过https://docs.microsoft.com/en-us/windows/uwp/maps-and-location/routes-and-directions

的这段代码

        //   Get the route between the points.
        MapRouteFinderResult routeResult =
              await MapRouteFinder.GetDrivingRouteAsync(
              new Geopoint(startLocation),
              new Geopoint(endLocation),
              MapRouteOptimization.Time,
              MapRouteRestrictions.None);

不幸的是，我因此出现了构建错误：

Severity    Code    Description Project File    Line    Suppression State
Error   CS4036  'IAsyncOperation<MapRouteFinderResult>' does not contain a 
definition for 'GetAwaiter' and no extension method 'GetAwaiter' accepting a 
first argument of type 'IAsyncOperation<MapRouteFinderResult>' could be found 
(are you missing a using directive for 'System'?)   

不确定是否缺少'System'的using指令？手段。