Sonata\ProductBundle\Model\BaseProductProvider::getCheapestEnabledVariation PHP Method

    public function getCheapestEnabledVariation(ProductInterface $product)
    {
        if (!$this->hasEnabledVariations($product)) {
            return;
        }
        $variations = $this->getEnabledVariations($product);
        $result = null;
        foreach ($variations as $productVariation) {
            if (null === $result || $productVariation->getPrice() < $result->getPrice()) {
                $result = $productVariation;
            }
        }
        return $result;
    }