This version of Unity is unsupported.

ShadowDrawingSettings.useRenderingLayerMaskTest

public bool useRenderingLayerMaskTest;

Description

Set this to true to make Unity filter Renderers during shadow rendering. Unity filters Renderers based on the Rendering Layer Mask of the Renderer itself, and the Rendering Layer Mask of each shadow casting Light.

Additional resources: Renderer.renderingLayerMask.