Edge SDK (specifically .NET) - getting current session user name in service request

With the .NET Edge SDK, is it possible to get the current session user name when processing a service request in a virtual thing?

For example, in the SteamSensor sample project, in the SteamThing.AddNumbers() method, is there some way to get the name of the user who initiated the request? Or is it necessary to add a 'username' input parameter to method and pass it in explicitly?