code: public void writeNamespace(String prefix, String namespaceURI)
  			throws XMLStreamException {
  		try {
  			this.exiAttributes.addNamespaceDeclaration(namespaceURI, prefix);
  			// encoder.encodeNamespaceDeclaration(namespaceURI, prefix);
  		} catch (Exception e) {
  			throw new XMLStreamException(e.getLocalizedMessage(), e);
  		}
  	}
docs: /*
  Writes a namespace to the output stream If the prefix argument to this
  method is the empty string, "xmlns", or null this method will delegate to
  writeDefaultNamespace
  
  (non-Javadoc)
  
  @see javax.xml.stream.XMLStreamWriter#writeNamespace(java.lang.String,
  java.lang.String)