Simplify cases in MultiBSDF
Simplify cases in MultiBSDF

Twinklebear/OSPRay,Twinklebear/OSPRay,MengjiaoH/ospray,Twinklebear/OSPRay,ospray/OSPRay,MengjiaoH/ospray,MengjiaoH/ospray,wilsonCernWq/ospray,Twinklebear/OSPRay,ospray/OSPRay,wilsonCernWq/ospray,wilsonCernWq/ospray,ospray/OSPRay,MengjiaoH/ospray,ospray/OSPRay,MengjiaoH/ospray