public function build($name, $node, \XMLWriter &$writer, $under_root)
{
// always inside an xsd:element
$writer->startElementNs('xsd', 'element', null);
$writer->writeAttribute('name', $name);
$this->addRequired($node, $writer, $under_root);
$writer->writeAttribute('type', 'xsd:boolean');
$writer->endElement();
}