Struts2 rest request asking for execute method - rest

Question

I am new to struts. I am writing a web application using struts2 rest. I have struts2 configured to accept both rest and non rest url. ( following http://struts.apache.org/release/2.3.x/docs/rest-plugin.html)
I expect "http://mylocalhost.com/myApp/detail" url to call DetailController class's index() method. However, I got this error :
java.lang.NoSuchMethodException: com.project.struts.rest.controllers.DetailController.execute()
java.lang.Class.getMethod(Class.java:1665)
It seems struts worked out it need to call detailController, but it tries to call the execute() method instead of the index() method.
Have I missed something in my struts config?
struts.xml configure file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<constant name="struts.devMode" value="true" />
<constant name="struts.action.extension" value="xhtml,,xml,json,action"/>
<constant name="struts.mapper.class" value="org.apache.struts2.dispatcher.mapper.PrefixBasedActionMapper" />
<constant name="struts.mapper.prefixMapping" value="/rest:rest,:struts"/>
<constant name="struts.convention.action.suffix" value="Controller"/>
<constant name="struts.convention.action.mapAllMatches" value="true"/>
<constant name="struts.convention.default.parent.package" value="rest-default"/>
<constant name="struts.convention.package.locators" value="controllers"/>
</struts>
I have a controller called DetailController in com.project.struts.rest.controllers
DetailController class:
package com.project.struts.rest.controllers;
import org.apache.struts2.rest.DefaultHttpHeaders;
import org.apache.struts2.rest.HttpHeaders;
import com.opensymphony.xwork2.ModelDriven;
public class DetailController implements ModelDriven<Object> {
private String propertyId;
#Override
public Object getModel() {
// TODO Auto-generated method stub
return null;
}
// GET /test/1
public HttpHeaders show() {
return new DefaultHttpHeaders("show");
}
// GET /test
public HttpHeaders index() {
return new DefaultHttpHeaders("index");
}
}