use null object pattern
use null object pattern



Former-commit-id: 8fc3ba230ca6e5f70adb58b9a45af1b6d4856e48
phatboyg/MassTransit,MassTransit/MassTransit,phatboyg/MassTransit,MassTransit/MassTransit,jacobpovar/MassTransit,SanSYS/MassTransit,jacobpovar/MassTransit,SanSYS/MassTransit