RAIN AMICO+ irrigation controller – what are the JACK socket under the cap and the rain sensor for?

Hello.
I have purchased a RAIN AMICO + irrigation controller, version 19.01.
At the rear of the control module there is a rubber cap concealing a JACK socket.
The manufacturer does not offer a dedicated rain sensor for this type of controller that could be connected to it, but I suspect this is a socket for controlling or shutting off the built-in solenoid valves.
Does anyone on our forum have any experience with this? What is this socket and what is it for?
Perhaps it’s possible to connect the contacts of a relay linked to a homemade sensor, or an original one after some adaptation.
Does this socket act as a SWITCH? It would be great if my assumptions were confirmed.
Best regards.
AI: Could you post a photo of this socket under the cover, as well as any markings on the casing or circuit board in the vicinity?
No.
AI: Does the manual, the box or the controller’s rating plate specify the exact version/model/revision of the device, and provide any information about the sensor input, accessories or service port?
No.

And this isn’t that sort of sensor: https://irrigationeasy.co.nz/products/rain-acqua-jack-rain-sensor-for-amico-vision-tap-timer?
However, it’s probably just a space in the casing or on the circuit board that isn’t connected to anything, if the manufacturer doesn’t mention it.
You can check this; a rain sensor generally works by breaking the circuit when it detects rain (there’s a limit switch and a ‘sponge’ that swells when wet – as the sponge swells, it breaks the contact and the station knows that it’s raining or has recently rained. Adjusting this sensor involves controlling how much air reaches the sponge – the more air, the faster it dries out, and so the sooner the watering will restart.
Knowing this, all you need to do is plug a two-pole (mono) 3.5mm jack into the socket whilst watering is in progress. If this open circuit causes the watering to stop, you’ll know that the whole system is working. Closing the circuit should restore operation.