+ public static Set<RecipientIdentifier.Username> getUsernameIdentifiers(Collection<String> usernameIdStrings) {
+ if (usernameIdStrings == null) {
+ return Set.of();
+ }
+ final var usernameIds = new HashSet<RecipientIdentifier.Username>();
+ for (final var usernameIdString : usernameIdStrings) {
+ usernameIds.add(new RecipientIdentifier.Username(usernameIdString));
+ }
+ return usernameIds;
+ }
+