hillshade
  The direction of the light source used to generate the hillshading with 0 as the top of the viewport if hillshade-illumination-anchor is set to viewport and due north if hillshade-illumination-anchor is set to map and no 3d lights enabled. If hillshade-illumination-anchor is set to map and 3d lights enabled, the direction from 3d lights is used instead.
Parameters
value of hillshadeIlluminationDirection
The direction of the light source used to generate the hillshading with 0 as the top of the viewport if hillshade-illumination-anchor is set to viewport and due north if hillshade-illumination-anchor is set to map and no 3d lights enabled. If hillshade-illumination-anchor is set to map and 3d lights enabled, the direction from 3d lights is used instead.
Parameters
value of hillshadeIlluminationDirection as Expression