public void beforeParsing(Document document) { var rootElement = new Element(document.getRootElement()); var existingValue = rootElement.getAttributeValue(FakeExtensionAttrName); var newValue = this.m_Text; if (existingValue != null) { newValue = existingValue + ", " + newValue; } rootElement.addAttribute(FakeExtensionAttrName, newValue); }