# File lib/new_relic/agent/instrumentation/action_controller_subscriber.rb, line 43
        def start_transaction(event)
          Transaction.start(state, :controller,
                            :request          => event.request,
                            :filtered_params  => filter(event.payload[:params]),
                            :apdex_start_time => event.queue_start,
                            :transaction_name => event.metric_name)
        end