+ var result = isRegistered(List.of(m.getUsername()));
+ return result.get(0);
+ }
+
+ @Override
+ public boolean isRegistered(String number) {
+ var result = isRegistered(List.of(number));
+ return result.get(0);
+ }
+
+ @Override
+ public List<Boolean> isRegistered(List<String> numbers) {
+ var results = new ArrayList<Boolean> ();
+ Map<String, Pair<String, UUID>> registered;
+ if (numbers.isEmpty()) {
+ return results;
+ }
+ try {
+ registered = m.areUsersRegistered(new HashSet<String>(numbers));
+ } catch (IOException e) {
+ throw new Error.Failure(e.getMessage());
+ }
+ for (String number : numbers) {
+ UUID uuid = registered.get(number).second();
+ results.add(uuid != null);
+ }
+ return results;