# File src/ruby_supportlib/phusion_passenger/vendor/union_station_hooks_core/lib/union_station_hooks_core/request_reporter/basics.rb, line 150
    def log_writing_rack_body_begin
      return do_nothing_on_null(:log_writing_rack_body_begin) if null?
      @transaction.log_activity_begin('app writing out response body')
      :writing_rack_body # Random non-nil ID
    end