Writes br tag.
XMLWriter $writer: Writer that writes the output.
DOMElement $node: Current node.
$id: Current node id.
protected function writeBR(\XMLWriter $writer, \DOMElement $node, $id) {
$writer
->startElement('x');
$writer
->writeAttribute('id', $id);
$writer
->writeAttribute('ctype', 'lb');
$writer
->endElement();
}