made some private vars readonly
made some private vars readonly



Former-commit-id: cd29a51557a8136a03037e02c160be8ec894ea11
jacobpovar/MassTransit,MassTransit/MassTransit,jacobpovar/MassTransit,MassTransit/MassTransit,phatboyg/MassTransit,SanSYS/MassTransit,phatboyg/MassTransit,SanSYS/MassTransit