public function exportValue(&$submitvalues, $assoc = false) {
        $valuearray = array();
        foreach ($this->_elements as $element) {
            $thisexport = $element->exportValue($submitvalues[$this->getName()], true);
            if ($thisexport != null) {
                $valuearray += $thisexport;
            }
        }
        if (empty($valuearray['customize'])) {
            return $this->_prepareValue(false, $assoc);
        }
        return array_key_exists('value', $valuearray) ? $this->_prepareValue($valuearray['value'], $assoc) : [];
    }