UnblockUser.php

<?php

namespace Drupal\user\Plugin\Action;

use Drupal\Core\Action\ActionBase;
use Drupal\Core\Session\AccountInterface;

/**
 * Unblocks a user.
 *
 * @Action(
 *   id = "user_unblock_user_action",
 *   label = @Translation("Unblock the selected users"),
 *   type = "user"
 * )
 */
class UnblockUser extends ActionBase {
    
    /**
     * {@inheritdoc}
     */
    public function execute($account = NULL) {
        // Skip unblocking user if they are already unblocked.
        if ($account !== FALSE && $account->isBlocked()) {
            $account->activate();
            $account->save();
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function access($object, AccountInterface $account = NULL, $return_as_object = FALSE) {
        
        /** @var \Drupal\user\UserInterface $object */
        $access = $object->status
            ->access('edit', $account, TRUE)
            ->andIf($object->access('update', $account, TRUE));
        return $return_as_object ? $access : $access->isAllowed();
    }

}