NavigationLayout.php

<?php

declare (strict_types=1);
namespace Drupal\navigation;

use Drupal\Core\Layout\LayoutDefault;
use Drupal\Core\Render\Element;

/**
 * Defines a layout class for navigation.
 *
 * @internal
 */
final class NavigationLayout extends LayoutDefault {
    
    /**
     * {@inheritdoc}
     */
    public function build(array $regions) {
        foreach (Element::children($regions) as $region_id) {
            foreach (Element::children($regions[$region_id]) as $component_uuid) {
                if (!Element::isEmpty($regions[$region_id][$component_uuid])) {
                    $regions[$region_id][$component_uuid]['#theme'] = 'block__navigation';
                }
            }
        }
        return parent::build($regions);
    }

}