Quote/EventListener/QuoteListener.php
protected function getSaleFromEvent(ResourceEventInterface $event)
    {
        $resource = $event->getResource();

        if (!$resource instanceof QuoteInterface) {
            throw new InvalidArgumentException("Expected instance of QuoteInterface");
        }

        return $resource;
    }
protected function getSaleFromEvent(ResourceEventInterface $event)
    {
        $resource = $event->getResource();

        if (!$resource instanceof QuoteInterface) {
            throw new InvalidArgumentException("Expected instance of QuoteInterface");
        }

        return $resource;
    }
@inheritdoc

@return QuoteInterface