code: private function getStock($variation)
      {
          $arrayStocks = [];
          $itemWarehouse = (int) $this->configService->get('item_warehouse', 0);
  
          static $warehouses;
  
          if (null === $warehouses) {
              $warehouses = $this->client->request('GET', 'stockmanagement/warehouses');
  
              $warehouses = array_filter($warehouses, function (array $warehouse) {
                  return $warehouse['typeId'] === self::SALES_WAREHOUSE;
              });
  
              $warehouses = array_column($warehouses, 'id');
          }
  
          foreach ($variation['stock'] as $stock) {
              if (!in_array($stock['warehouseId'], $warehouses, true)) {
                  continue;
              }
  
              if ($itemWarehouse !== 0 && $stock['warehouseId'] !== $itemWarehouse) {
                  continue;
              }
  
              if ($stock['variationId'] !== $variation['id']) {
                  continue;
              }
  
              $arrayStocks[] = $stock['netStock'];
          }
  
          return (float) array_sum($arrayStocks);
      }
docs: @param array $variation
  
  @return float