Random generator?

Is there a random generator in openhab?

Openhab will grab analogue values from a light sensor, compare to a threshold, to determine when to close curtains.
I wish to add some ‘jitter’ so that the curtains are not seen to close at the same time every day.

I envisage doing this by either adding a random amount to the read-in analogue lux value, or adding a random amount to the threshold, or adding a random amount of time to the calculated closure time.

Here is a topic with some usage of Java’s random function: