public function addNested(VariationInterface $variation) : VariationInterface
    {
        $this->configResolver->addCallback($this);
        $this->nested[] = $variation;

        return $this;
    }
public function addNested(VariationInterface $variation) : VariationInterface
    {
        $this->configResolver->addCallback($this);
        $this->nested[] = $variation;

        return $this;
    }
{@inheritdoc}