private function validateUppercaseLetter(): bool
    {
        if ($this->options['require-uppercase-letter'] === true) {
            if (!\preg_match('/[A-Z]/u', (string)$this->value)) {
                $this->setError(self::VALIDATOR_ERROR_PASSWORD_MUST_CONTAIN_UPPERCASE_LETTER);
                return false;
            }
        }
        return true;
    }