GeofenceID to Forward URL (json)

Hello experts,

How to append the [geofenceid] to a "forward.url"?
According to the documentation, only parameters that are in [positions] are possible.
Unfortunately, event.forward.url does not work with json.

here my traccar.xml.

<!-- URL Data forward to mqtt broker -->
<entry key='forward.enable'>true</entry>
<entry key='forward.url'>http://192.168.178.44:32798</entry>
<entry key='forward.json'>true</entry>
<entry key='event.forward.enable'>true</entry>
<entry key='event.forward.url'>http://192.168.178.44:32798</entry>
<entry key='event.forward.header'>
X-myheader: Traccar Forward Event
Y-another: DS918 Traccar Server

I use a Docker container that can read the "position" and "device" information. I get this through "forward.url" in the "json".
The server version is also an older one. V 4,021.

Thank you very much

Gruss Denny

Event forward always sends JSON.