private void notifyOtherExchangeParticipant(
     String userEmail, DirectBookExchange directExchangeToReject) {
   if (directExchangeToReject.getExchangeInitiatorEmail().equals(userEmail)) {
     raiseDirectExchangeRejectedNotification(
         excahngeRejecteUserUnderOfferdMessage, directExchangeToReject.getUserUnderOffer());
   } else {
     raiseDirectExchangeRejectedNotification(
         exchangeRejectedInitiatorMessage, directExchangeToReject.getExchangeInitiator());
   }
 }