Fix change from Guid? to Guid
Fix change from Guid? to Guid

dotnet/roslyn,dotnet/roslyn,diryboy/roslyn,stephentoub/roslyn,weltkante/roslyn,bartdesmet/roslyn,sharwell/roslyn,KirillOsenkov/roslyn,stephentoub/roslyn,CyrusNajmabadi/roslyn,sharwell/roslyn,CyrusNajmabadi/roslyn,panopticoncentral/roslyn,shyamnamboodiripad/roslyn,tannergooding/roslyn,AlekseyTs/roslyn,mavasani/roslyn,physhi/roslyn,tmat/roslyn,panopticoncentral/roslyn,AmadeusW/roslyn,mgoertz-msft/roslyn,tannergooding/roslyn,sharwell/roslyn,KevinRansom/roslyn,panopticoncentral/roslyn,diryboy/roslyn,heejaechang/roslyn,eriawan/roslyn,tannergooding/roslyn,tmat/roslyn,physhi/roslyn,physhi/roslyn,mgoertz-msft/roslyn,mavasani/roslyn,shyamnamboodiripad/roslyn,diryboy/roslyn,jasonmalinowski/roslyn,CyrusNajmabadi/roslyn,AlekseyTs/roslyn,bartdesmet/roslyn,ErikSchierboom/roslyn,AmadeusW/roslyn,mgoertz-msft/roslyn,wvdd007/roslyn,heejaechang/roslyn,KirillOsenkov/roslyn,bartdesmet/roslyn,KevinRansom/roslyn,jasonmalinowski/roslyn,eriawan/roslyn,gafter/roslyn,wvdd007/roslyn,AmadeusW/roslyn,gafter/roslyn,mavasani/roslyn,KevinRansom/roslyn,gafter/roslyn,eriawan/roslyn,shyamnamboodiripad/roslyn,weltkante/roslyn,stephentoub/roslyn,KirillOsenkov/roslyn,tmat/roslyn,ErikSchierboom/roslyn,AlekseyTs/roslyn,wvdd007/roslyn,ErikSchierboom/roslyn,heejaechang/roslyn,jasonmalinowski/roslyn,dotnet/roslyn,weltkante/roslyn