final RandomProviderImpl random =
// TODO(ohler): Get a stronger RandomProvider.
RandomProviderImpl.ofSeed(randomSeed);
final RandomBase64Generator random64 = new RandomBase64Generator(new RandomProvider() {
@Override public int nextInt(int upperBound) {
return random.nextInt(upperBound);
}});
final ParticipantId userId;
try {
userId = ParticipantId.of(userIdString);
} catch (InvalidParticipantAddress e1) {