public class RestCredentialVerifier implements ICredentialVerifier {
  private static final Logger LOG = LoggerFactory.getLogger(RestCredentialVerifier.class);

  @Override
  public int verify(String username, char[] passwordPlainText) throws IOException {

    // Test for missing username or password
    if (StringUtility.isNullOrEmpty(username) || passwordPlainText == null
        || passwordPlainText.length == 0) {
      LOG.warn(TEXTS.get("MissingUsernameOrPassword"));
      throw new VetoException(TEXTS.get("MissingUsernameOrPassword")).withSeverity(IStatus.WARNING);
    }

    // Test for non-conforming password
    // Password MUST have between 8 to 20 characters with a minimum of one uppercase, one lowercase,
    // one number, one special character and without spaces
    if ((passwordPlainText.length < 8) || (passwordPlainText.length > 20)) {
      LOG.warn(TEXTS.get("ThePasswordMustHaveBetween820Characters"));
      throw new VetoException(TEXTS.get("ThePasswordMustHaveBetween820Characters")).withSeverity(IStatus.WARNING);
    }

    if (passwordInvalid(String.valueOf(passwordPlainText))) {
      LOG.warn(TEXTS.get("PasswordCompositionRuleWarning"));
      throw new VetoException(TEXTS.get("PasswordCompositionRuleWarning")).withSeverity(IStatus.WARNING);
    }

    // .... more code here

    return result;
  }
}