Questions about BoTSORT::track

[Jierui]

After reading the BoTSORT::track function carefully, I have the following questions:
// Segregate tracks in unconfirmed and tracked tracks
std::vector<std::shared_ptr> unconfirmed_tracks, tracked_tracks;
for (const std::shared_ptr &track: _tracked_tracks)
{
if (!track->is_activated)
{
unconfirmed_tracks.push_back(track);
}
else
{
tracked_tracks.push_back(track);
}
}
In this code, there will be no data with is_activated set to false in the _tracked_tracks array. I looked carefully and found that there is no other place that sets is_activated to false except for the track constructor. Is it because I didn't understand it well and missed some scenarios, or is the code itself designed like this? I hope the author can help answer my doubts. Thank you very much.