entity_reference_revisions-8.x-1.x-dev/src/Plugin/Field/FieldFormatter/EntityReferenceRevisionsFormatterBase.php

<?php

namespace Drupal\entity_reference_revisions\Plugin\Field\FieldFormatter;

use Drupal\Core\Field\Plugin\Field\FieldFormatter\EntityReferenceFormatterBase;

/**
 * Parent plugin for entity reference formatters.
 */
abstract class EntityReferenceRevisionsFormatterBase extends EntityReferenceFormatterBase {

  /**
   * {@inheritdoc}
   */
  public function prepareView(array $entities_items) {
    // Entity revision loading currently has no static/persistent cache and no
    // multiload. As entity reference checks _loaded, while we don't want to
    // indicate a loaded entity, when there is none, as it could cause errors,
    // we actually load the entity and set the flag.
    foreach ($entities_items as $items) {
      foreach ($items as $item) {

        if ($item->entity) {
          $item->_loaded = TRUE;
        }
      }
    }
  }

}