code: public Set<Subscriber> findUsersForNotification(String notificationDispatcherKey, String notificationChannelKey, @Nullable String projectKey) {
      try (DbSession session = mybatis.openSession(false)) {
        return getMapper(session).findUsersForNotification(NOTIFICATION_PREFIX + notificationDispatcherKey + "." + notificationChannelKey, projectKey);
      }
    }
docs: Returns the logins of users who have subscribed to the given notification dispatcher with the given notification channel.
  If a resource ID is passed, the search is made on users who have specifically subscribed for the given resource.
  
  Note that {@link  UserRole#USER} permission is not checked here, filter the results with
  {@link org.sonar.db.permission.AuthorizationDao#keepAuthorizedLoginsOnProject}
  
  @return the list of Subscriber (maybe be empty - obviously)