CommentTestController.php

<?php

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'),
        ];
    }

}