pm-4.1.x-dev/src/BundleFieldDefinition.php

<?php

namespace Drupal\pm;

use Drupal\Core\Field\BaseFieldDefinition;

/**
 * Provides a field definition class for bundle fields.
 *
 * Core currently doesn't provide one, the hook_entity_bundle_field_info()
 * example uses BaseFieldDefinition, which is wrong. Tracked in #2346347.
 *
 * Note that this class implements both FieldStorageDefinitionInterface and
 * FieldDefinitionInterface. This is a simplification for DX reasons,
 * allowing code to return just the bundle definitions instead of having to
 * return both storage definitions and bundle definitions.
 */
class BundleFieldDefinition extends BaseFieldDefinition {

  /**
   * {@inheritdoc}
   */
  public function isBaseField() {
    return FALSE;
  }

}