class ElasticAPM::Span

def done
  @duration = Util.micros - @transaction.timestamp - relative_start
  if original_backtrace && long_enough_for_stacktrace?
    @stacktrace =
      @transaction.instrumenter.agent.stacktrace_builder.build(
        original_backtrace, type: :span
      )
  end
  self.original_backtrace = nil # release it
  self
end