A shadow appears on an object illuminated by light passing trough a CoronaLightMtl with "Emit Light" off.
To reproduce:
Set up a scene with a single Corona light and a Plane object.
Put a CoronaMtl on the plane and set the Reflection to 1,0.
Create any Object between the Plane and the light so that the Object cast a shadow on the Plane.
Add a CoronaLightMtl to the Object and turn off the "Emit Light" in the CoronaLightMtl. There should be no shadow visible on the Plane.
Go back to the CoronaMtl and slide the Reflection Glossiness value to about 0,35. A shadow should start to appear on the Plane. The appearance depends on the glossiness and IOR value.
