async function onVolumeEvent(deviceUuid, volume) {
  const newState = {
    device_feature_external_id: `sonos:${deviceUuid}:volume`,
    state: volume,
  };
  this.gladys.event.emit(EVENTS.DEVICE.NEW_STATE, newState);
}
@description When the volume change.
@param {string} deviceUuid - Sonos internal UUID.
@param {number} volume - Sonos volume level.
@example onAvTransportEvent('toto', data);