internal Uri ToUri()
{
this.EnsureSensor(true);
var qsb = new Internal.QueryStringBuilder()
.Append("origins", WaypointsToUri(_waypointsOrigin))
.Append("destinations", WaypointsToUri(_waypointsDestination))
.Append("mode", Mode.ToString())
.Append("language", Language)
.Append("units", Units.ToString())
.Append("sensor", (Sensor.Value ? "true" : "false"))
.Append("avoid", AvoidHelper.MakeAvoidString(Avoid));
var url = "json?" + qsb.ToString();
return new Uri(url, UriKind.Relative);
}