CommentTestController.php

<?php

declare (strict_types=1);
namespace Drupal\comment_test\Controller;

use Drupal\comment\CommentInterface;
use Drupal\Core\Controller\ControllerBase;

/**
 * Controller for the comment_test.module.
 */
class CommentTestController extends ControllerBase {
  
  /**
   * Provides a comment report.
   */
  public function commentReport(CommentInterface $comment) {
    return [
      '#markup' => $this->t('Report for a comment'),
    ];
  }

}