EntityTestViewBuilder.php

<?php

namespace Drupal\entity_test;

use Drupal\Core\Entity\EntityViewBuilder;

/**
 * Defines an entity view builder for a test entity.
 *
 * @see \Drupal\entity_test\Entity\EntityTestRender
 */
class EntityTestViewBuilder extends EntityViewBuilder {
    
    /**
     * {@inheritdoc}
     */
    public function buildComponents(array &$build, array $entities, array $displays, $view_mode) {
        parent::buildComponents($build, $entities, $displays, $view_mode);
        foreach ($entities as $id => $entity) {
            $build[$id]['label'] = [
                '#weight' => -100,
                '#plain_text' => $entity->label(),
            ];
            $build[$id]['separator'] = [
                '#weight' => -150,
                '#markup' => ' | ',
            ];
            $build[$id]['view_mode'] = [
                '#weight' => -200,
                '#plain_text' => $view_mode,
            ];
        }
    }

}