why attributes is empty when forward data

<!--    <entry key='event.forward.url'>http://18.xxxxxxxxx:3000/traccar</entry>-->
<!--    <entry key='event.forward.header'>Content-Type: application/json</entry>--> 

{'event': {'id': 43334, 'attributes': {}, 'deviceId': 385, 'type': 'deviceOffline', 'eventTime': '2024-05-10T10:45:34.984+00:00', 'positionId': 0, 'geofenceId': 0, 'maintenanceId': 0}, 'device': {'id': 385, 'attributes': {}, 'groupId': 0, 'calendarId': 0, 'name': '868618052108909', 'uniqueId': '868618052108909', 'status': 'offline', 'lastUpdate': '2024-05-10T10:45:07.076+00:00', 'positionId': 0, 'phone': None, 'model': None, 'contact': None, 'category': None, 'disabled': False, 'expirationTime': None}}

Why and what attributes are you expecting?