Утилита X, thenError

static <T, R> Future<R> thenError(
    final Future<Boolean> условие, 
    final Supplier<Future<T>> trueFuture, 
    final Function<T, R> trueFun, 
    final Class<? extends WebException> clazz, 
    final Object... args)
static Future<JsonObject> thenError(
    final Future<Boolean> condition, 
    final Supplier<Future<JsonObject>> trueFuture, 
    final Class<? extends WebException> clazz, 
    final Object... args)
static <T> Future<T> thenError(
    final Class<? extends WebException> clazz, 
    final Object... args)

public Function<SecUser, Future<JsonObject>> response(
        final String username,
        final String password,
        final Function<SecUser, Future<JsonObject>> future) {
    return pojo -> {
        if (null == pojo) {
            // Пользователь не существует
            this.logger.info("[ Auth ] username/id = {0} does not exist.", username);
            return Ux.thenError(UserNotFoundException.class, this.clazz, username);
        } else if (!password.equals(pojo.getSPassword())) {
            // Пароль неправильный
            this.logger.info("[ Auth ] username/id = {0}, password is wrong {1}.", username, password);
            return Ux.thenError(PasswordWrongException.class, this.clazz, username);
        } else {
            // Продолжаем, потому что успешно
            this.logger.info("[ Auth ] User ( username/id = {0} ) login successfully.", username);
            return future.apply(pojo);
        }
    };
}