public async Task <IHttpActionResult> PutUpdateSensorUser(int sensorId, int environmentId)
        {
            var userId = SecurityHelpers.ValidateToken(Request.Headers);
            var apiKey = await api.RegisterSensor(userId, sensorId, environmentId);


            return(apiKey.StartsWith("Error") ? (IHttpActionResult)BadRequest(apiKey) : Ok(apiKey));
        }