When processing the 'Activate' directive for the SceneController interface, how do you determine what caused the Activate to be triggered? It is not included in the request itself and in the payload for the response, a 'cause' object is required. In the example provided at https://github.com/alexa/alexa-smarthome/blob/master/sample_messages/SceneController/SceneController.ActivationStarted.message.json the cause.type is 'VOICE_INTERACTION'. Is that the only possible cause type for a Scene? APP_INTERACTION seems like a reasonable cause as well.