PreferencesFxUtils { public static List<Setting> categoriesToSettings(List<Category> categories) { return categories.stream() .map(Category::getGroups) .filter(Objects::nonNull) .flatMap(Collection::stream) .map(Group::getSettings) .filter(Objects::nonNull) .flatMap(Collection::stream) .collect(Collectors.toList()); }  static List<Setting> categoriesToSettings(List<Category> categories); static List<Element> categoriesToElements(List<Category> categories); static HashMap<Setting, Category> mapSettingsToCategories(List<Category> categories); static HashMap<Group, Category> mapGroupsToCategories(List<Category> categories); static List<Category> filterCategoriesByDescription(List<Category> categories,
                                                             String description); static List<Setting> filterSettingsByDescription(List<Setting> settings,
                                                          String description); static List<Setting> groupsToSettings(List<Group> groups); static List<Group> filterGroupsByDescription(List<Group> groups, String description); static List<Group> categoriesToGroups(List<Category> categories); static int getRowCount(GridPane gridPane); static List<Category> flattenCategories(List<Category> categoryLst);  }
@Ignore @Test public void categoriesToSettings() throws Exception { }