private function isNullOrEqualsParentData(CharacteristicInterface $characteristic)
    {
        if ($characteristic->isNull()) {
            return true;
        } elseif (null !== $this->parentDatas &&
            null !== $parentCharacteristic = $this->parentDatas->findCharacteristicByIdentifier($characteristic->getIdentifier())) {
            return $parentCharacteristic->equals($characteristic);
        }

        return false;
    }