public function process()
    {
        if (!$this->getForm()->isSubmitted()) {
            return;
        }

        parent::process();

        $this->processValues();

        if (
            $this->required &&
            count($this->values) == 0 &&
            $this->isSensitive()
        ) {
            $this->addMessage($this->getValidationMessage('required'));
        }
    }