All classes that implement OrderPromotionOfferInterface in Commerce Core 8.2

class \Drupal\commerce_currency_resolver\Plugin\Commerce\PromotionOffer\OrderFixedAmountOff uses CommerceCurrencyResolverAmountTrait
class \Drupal\commerce_promotion\Plugin\Commerce\PromotionOffer\BuyXGetY
class \Drupal\commerce_promotion\Plugin\Commerce\PromotionOffer\CombinationOffer implements CombinationOfferInterface
class \Drupal\commerce_promotion\Plugin\Commerce\PromotionOffer\OrderFixedAmountOff uses FixedAmountOffTrait
class \Drupal\commerce_promotion\Plugin\Commerce\PromotionOffer\OrderPercentageOff uses PercentageOffTrait
class \Drupal\commerce_promotion\Plugin\Commerce\PromotionOffer\OrderPromotionOfferBase implements OrderPromotionOfferInterface

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