writeNamespace(XMLConstants.DEFAULT_NS_PREFIX, namespaceURI);
if (!inStartElement) throw new IllegalStateException(); if (!isURI(namespaceURI)) throw new IllegalArgumentException("illegal URI: " + namespaceURI); writeNamespaceImpl(XMLConstants.DEFAULT_NS_PREFIX, namespaceURI);
  public void writeDefaultNamespace(String namespaceURI)    throws XMLStreamException  {    writeNamespace(XMLConstants.DEFAULT_NS_PREFIX, namespaceURI);  }