code: public void setSubscriptions(List<String> subscriptions) {
          this.subscriptions.clear();
          if(subscriptions == null) return;
          for(String currentSubscription: subscriptions) {
              if (this.getNotifierName().equals(AlertService.SupportedNotifier.GUS.getName())) {
                  if (currentSubscription.isEmpty() || currentSubscription.length() < 10)
                      throw new IllegalArgumentException("GUS Subscription has to contain subjectId with more than 10 characters.");
              } else if (this.getNotifierName().equals(AlertService.SupportedNotifier.EMAIL.getName())) {
  
                  if (currentSubscription.isEmpty() || !currentSubscription.contains("@")) {
                      String errorMessage = MessageFormat.format("Email Address {0} is not allowed as @ not present.",
                              currentSubscription);
                      throw new IllegalArgumentException(errorMessage);
                  }
              } else if (this.getNotifierName().equals(AlertService.SupportedNotifier.CALLBACK.getName()) && currentSubscription.isEmpty()) {
                  throw new IllegalArgumentException("Callback Notifier Subscription cannot be empty.");
              }
          }
          if (subscriptions != null && !subscriptions.isEmpty()) {
              this.subscriptions.addAll(subscriptions);
          }
      }
docs: Replaces the subscriptions used by the notifier to send the notifications.
  
  @param  subscriptions  The subscription list.