public static function getChildren(SKU $sku) {
    $children = [];

    foreach ($sku->get('field_configured_skus')->getValue() as $child) {
      if (empty($child['value'])) {
        continue;
      }

      $child_sku = SKU::loadFromSku($child['value']);
      if ($child_sku instanceof SKU) {
        $children[$child_sku->getSKU()] = $child_sku;
      }
    }

    return $children;
  }