Administration page

HolidayStructure.php

<?php

namespace Drupal\home_holiday\Controller;

use Drupal\Core\Controller\ControllerBase;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Drupal\system\SystemManager;

/**
 * Class HolidayStructure.
 */
class HolidayStructure extends ControllerBase {

  /**
   * Drupal\system\SystemManager definition.
   *
   * @var \Drupal\system\SystemManager
   */
  protected $systemManager;

  /**
   * Constructs a new HolidayStructure object.
   */
  public function __construct(SystemManager $system_manager) {
    $this->systemManager = $system_manager;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static(
      $container->get('system.manager')
    );
  }

  /**
   * Hello.
   *
   * @return array
   *
   */
  public function structure() {
    return $this->systemManager->getBlockContents();
  }

}