protected function getSkuFieldName($node_type) {
    $fields = $this->entityFieldManager
      ->getFieldDefinitions('node', $node_type);

    // Determine which field is used for sku references based on the configured
    // product node type.
    $sku_field_name = FALSE;
    foreach ($fields as $field_name => $field_instance) {
      $field_type = $field_instance->getType();
      if ($field_type == 'sku') {
        $sku_field_name = $field_name;
        break;
      }
    }

    return $sku_field_name;
  }