OpenHAB - Garage door open timer

var Timer garageDoorTimer = null
rule "open mower garage door"
when
    Item RasenmaehernaechsterStart changed or
    System started
then
    val timerTime = new DateTime(RasenmaehernaechsterStart.state.toString).minusMinutes(5)
    if (garageDoorTimer !== null) {
        garageDoorTimer.reschedule(timerTime)
    } else {
        garageDoorTimer = createTimer(timerTime.millis,
        [ |
            ShellyGarageRoboterRollerControl.sendCommang(UP)
        ])
    }
end