src/Model/Variation/OrderItem.php
public function ProductVariation($forcecurrent = false)
    {
        if ($this->ProductVariationID && $this->ProductVariationVersion && !$forcecurrent) {
            return Versioned::get_version(
                Variation::class,
                $this->ProductVariationID,
                $this->ProductVariationVersion
            );
        } elseif ($this->ProductVariationID
            && $product = Variation::get()->byID($this->ProductVariationID)
        ) {
            return $product;
        }
        return null;
    }
public function ProductVariation($forcecurrent = false)
    {
        if ($this->ProductVariationID && $this->ProductVariationVersion && !$forcecurrent) {
            return Versioned::get_version(
                Variation::class,
                $this->ProductVariationID,
                $this->ProductVariationVersion
            );
        } elseif ($this->ProductVariationID
            && $product = Variation::get()->byID($this->ProductVariationID)
        ) {
            return $product;
        }
        return null;
    }
Overloaded relationship, for getting versioned variations

@param  boolean $current
@return Variation