# File lib/new_relic/agent/transaction/external_request_segment.rb, line 34
        def add_request_headers request
          process_host_header request
          return unless record_metrics? && CrossAppTracing.cross_app_enabled?

          transaction_state.is_cross_app_caller = true
          txn_guid = transaction_state.request_guid
          trip_id   = transaction && transaction.cat_trip_id(transaction_state)
          path_hash = transaction && transaction.cat_path_hash(transaction_state)
          synthetics_header = transaction && transaction.raw_synthetics_header

          CrossAppTracing.insert_request_headers request, txn_guid, trip_id, path_hash, synthetics_header
        rescue => e
          NewRelic::Agent.logger.error "Error in add_request_headers", e
        end