class UsernameGenerator {

  public StringCredentialValue generateCredential() {
    final StringGenerationParameters parameters = new StringGenerationParameters();
    parameters.setLength(20);
    parameters.setExcludeNumber(true);

    return passayStringCredentialGenerator.generateCredential(parameters);
  }

  @Autowired  UsernameGenerator(final PassayStringCredentialGenerator passayStringCredentialGenerator);

}