NodeTypeAccessControlHandler.php

<?php

namespace Drupal\node;

use Drupal\Core\Access\AccessResult;
use Drupal\Core\Entity\EntityAccessControlHandler;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Session\AccountInterface;

/**
 * Defines the access control handler for the node type entity type.
 *
 * @see \Drupal\node\Entity\NodeType
 */
class NodeTypeAccessControlHandler extends EntityAccessControlHandler {
    
    /**
     * {@inheritdoc}
     */
    protected function checkAccess(EntityInterface $entity, $operation, AccountInterface $account) {
        switch ($operation) {
            case 'view':
                return AccessResult::allowedIfHasPermission($account, 'access content');
            case 'delete':
                if ($entity->isLocked()) {
                    return AccessResult::forbidden()->addCacheableDependency($entity);
                }
                else {
                    return parent::checkAccess($entity, $operation, $account)->addCacheableDependency($entity);
                }
                break;
            default:
                return parent::checkAccess($entity, $operation, $account);
        }
    }

}