Longman\TelegramBot\Entities\KeyboardButton::validate PHP Method

    protected function validate()
    {
        if ($this->getProperty('text', '') === '') {
            throw new TelegramException('You must add some text to the button!');
        }
        if ($this->getRequestContact() && $this->getRequestLocation()) {
            throw new TelegramException('You must use only one of these fields: request_contact, request_location!');
        }
    }