Including JavaScript file in the Head of the page from portlet

One of the common requirement for portlet developer is how do i include a JavaScript file in the Head section of portal response page. I used the concept of Two phase rendering to build a sample portlet that includes JavaScript file in the head of the portal response.

This is how my TwoPhaseRenderPortlet.java looks like

package com.ibm.webspherenotes.jsr286;

import java.io.IOException;

import javax.portlet.GenericPortlet;
import javax.portlet.MimeResponse;
import javax.portlet.PortletException;
import javax.portlet.RenderRequest;
import javax.portlet.RenderResponse;

import org.w3c.dom.Element;

public class TwoPhaseRenderingPortlet extends GenericPortlet{
 protected void doHeaders(RenderRequest request, RenderResponse response) {
  System.out.println("Entering TwoPhaseRenderingPortlet.doHeaders()");
  Element script = response.createElement("script");
  script.setAttribute("type", "text/javascript");
  script.setAttribute("src", request.getContextPath()+"/js/test.js");
  response.addProperty(MimeResponse.MARKUP_HEAD_ELEMENT, script); 
  
  System.out.println("Exiting TwoPhaseRenderingPortlet.doHeaders()");
 }
 protected void doView(RenderRequest request, RenderResponse response)
   throws PortletException, IOException {
  System.out.println("Entering TwoPhaseRenderingPortlet.doView()");
  response.setContentType("text/html");
  response.getWriter().println("Hello from two phase rendering portlet");
  System.out.println("Exiting TwoPhaseRenderingPortlet.doView()");
 }
}

In the doHeaders() method i am creating a script element and setting its src attribute to point to test.js which is part of the portlet web application.
This approach is same as that i used for changing portal page title

When i access the page with the portlet, i can see the test.js being called, i kept this invalid URL so that its easier to see in firebug