+ // Add "special" groups
+ groups.put("*", getAuthorsGroup(authors, '*'));
+ groups.put("0-9", getAuthorsGroup(authors, '0'));
+
+ // Prune empty groups
+ keys = new ArrayList<String>(groups.keySet());
+ for (String key : keys) {
+ if (groups.get(key).isEmpty()) {
+ groups.remove(key);