private NewsGroup convert(Echoarea area, Auth auth) {
Collection<Entity> entities = retrieveEntities(area.getId(), auth);
NewsGroup newsGroup = new NewsGroup();
newsGroup.setId(area.getId());
newsGroup.setName(area.getName());
newsGroup.setReportedLowWatermark(countLowWatermark(entities));
newsGroup.setReportedHighWatermark(countHighWatermark(entities));
newsGroup.setNumberOfArticles(countArticles(entities));
return newsGroup;
}