widget_engine-8.x-1.2/src/WidgetEngineViewBuilder.php

<?php

namespace Drupal\widget_engine;

use Drupal\Core\Entity\Display\EntityViewDisplayInterface;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Entity\EntityViewBuilder;

/**
 * View builder handler for widgets.
 */
class WidgetEngineViewBuilder extends EntityViewBuilder {

  /**
   * {@inheritdoc}
   */
  protected function alterBuild(array &$build, EntityInterface $entity, EntityViewDisplayInterface $display, $view_mode) {

    parent::alterBuild($build, $entity, $display, $view_mode);
    if ($entity->id()) {
      $build['#contextual_links']['widget'] = [
        'route_parameters' => ['widget' => $entity->id()],
      ];
    }
  }

}