opts.tasks = task.Descendents()
	slices.SortStableFunc(opts.tasks, func(a, b *trace.UserTaskSummary) int {
		aStart, bStart := parsed.startTime(), parsed.startTime()
		if a.Start != nil {
			aStart = a.Start.Time()
		}
		if b.Start != nil {
			bStart = b.Start.Time()
		}
		if a.Start != b.Start {
			return cmp.Compare(aStart, bStart)
		}
		// Break ties with the end time.
		aEnd, bEnd := parsed.endTime(), parsed.endTime()

      auto fbb = std::make_unique<flexbuffers::Builder>();
      size_t map_start = fbb->StartMap();
      for (const NamedAttribute& pair : composite.getCompositeAttributes()) {
        // Allows skipping unsupported attributes, will warn.
        (void)BuildOption(fbb.get(), op, pair);
      }
      fbb->EndMap(map_start);
      fbb->Finish();
      custom_option_buffer.assign(fbb->GetBuffer().begin(),