attachOffersToSubscriptions(member, subscriptionOffers) {
        member.subscriptions = member.subscriptions.map((subscription) => {
            const offer = subscriptionOffers.get(subscription.id);
            if (offer) {
                subscription.offer = offer;
            } else {
                subscription.offer = null;
            }
            return subscription;
        });
    }
@private
@param {Object} member JSON serialized member
@param {Map<string, OfferDTO>} subscriptionOffers result from fetchSubscriptionOffers