eZ\Publish\Core\FieldType\RichText\Converter::convert PHP Method

    public function convert(DOMDocument $xmlDoc);

 /**
  * {@inheritDoc}
  */
 public function postProcessValueHash($outgoingValueHash)
 {
     $document = new DOMDocument();
     $document->loadXML($outgoingValueHash['xml']);
     $outgoingValueHash['xhtml5edit'] = $this->docbookToXhtml5EditConverter->convert($document)->saveXML();
     return $outgoingValueHash;
 }