public function evaluateFieldValue($value)
    {
        $extConf = GeneralUtility::makeInstance(ExtensionConfiguration::class)->get('ke_search');
        $minLength = isset($extConf['searchWordLength']) ? (int) $extConf['searchWordLength'] : 4;

        if (strlen($value) < $minLength) {
            /** @var \TYPO3\CMS\Core\Messaging\FlashMessage $message */
            $message = GeneralUtility::makeInstance(
                \TYPO3\CMS\Core\Messaging\FlashMessage::class,
                $this->translate('tag_too_short_message', [$value, $minLength]),
                $this->translate('tag_too_short'),
                \TYPO3\CMS\Core\Messaging\FlashMessage::ERROR,
                true
            );

            /** @var $flashMessageService \TYPO3\CMS\Core\Messaging\FlashMessageService */
            $flashMessageService = GeneralUtility::makeInstance(\TYPO3\CMS\Core\Messaging\FlashMessageService::class);
            $flashMessageService->getMessageQueueByIdentifier()->addMessage($message);
            return false;
        }
        return $value;
    }