code: public ListIterator<Parameterable> getParameterableHeaders(String name)
  			throws ServletParseException {
  
  		ListIterator<Header> headers = this.message
  				.getHeaders(getCorrectHeaderName(name));
  
  		ArrayList<Parameterable> result = new ArrayList<Parameterable>();
  
  		while (headers != null && headers.hasNext())
  			result.add(createParameterable(headers.next(),
  					getFullHeaderName(name), message instanceof Request));
  
  		if(!isParameterable(name)) {
  			throw new ServletParseException(name + " header is not parameterable !");
  		}
  
  		return result.listIterator();
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipServletMessage#getParameterableHeaders(java.lang.String)