namespace Drupal\comment\Plugin\views\sort

Classsort descending Location Description
NcsLastCommentName drupal/core/modules/comment/lib/Drupal/comment/Plugin/views/sort/NcsLastCommentName.php Sort handler to sort by last comment name which might be in 2 different fields.
NcsLastUpdated drupal/core/modules/comment/lib/Drupal/comment/Plugin/views/sort/NcsLastUpdated.php Sort handler for the newer of last comment / node updated.
Thread drupal/core/modules/comment/lib/Drupal/comment/Plugin/views/sort/Thread.php Sort handler for ordering by thread.