SPRINGFIELD — A union-backed bill putting primary contractors on the hook for wage theft committed by their subcontractors is facing opposition in the General Assembly from minority contractor trade groups.The measure, House Bill 5412, makes primary contractors — those who contract directly with the customer — liable for wages, fringe benefits and attorney’s fees if the subcontractors they hire fail to pay their employees.In other words, it allows a worker with a grievance against the subcontractor …