VRay_Matte_ShadowColor in V-Ray 5.0 (NEXT)

I have a script that changes some of the V-Ray Object Properties to the ones I need. For V-Ray 3.40, it works as it should. But when I tried to use it for V-Ray NEXT, I ran into the fact that this line does not assign the desired color to the shadow. I can't find any documentation for the new V-Ray. Who can tell in what format the color should be recorded?

setUserProp $ "VRay_Matte_ShadowColor" ([128.0, 128.0, 128.0] / 255.0)

The rest of the lines that affect the values of true or false are processed as before:

For example:

setUserProp $ "VRay_Matte_ShadowBrightness" 1

There was a discussion in this thread. And there are some specific color parameters for this option. But what is this form of writing color, I also could not find ...: