+ final var usernames = ns.<String>getList("username");
+ final Map<String, UsernameStatus> registeredUsernames;
+ try {
+ registeredUsernames = usernames == null ? Map.of() : m.getUsernameStatus(new HashSet<>(usernames));
+ } catch (IOException e) {
+ throw new IOErrorException("Unable to check if users are registered: "
+ + e.getMessage()
+ + " ("
+ + e.getClass().getSimpleName()
+ + ")", e);
+ }
+