I want to use json with Struts2. However, when I set the action return type to "json", I got "there is no result type defined for type 'json' mapped with name 'success'." Bellow is struts.xml 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.custom.i18n.resources" value="resource"/>

    <package extends="struts-default" name="test">
        <action name="inputHandler" class="inputHandlerAction">
            <result name="input">/index.jsp</result>
            <result>/result.jsp</result>
        </action>
        <action name="setLangHandler" class="com.sesoft.test.setLanguageHandler">
            <result>/index.jsp</result>
        </action>

        <action name="Handler" class="com.sesoft.test.Handler">
            <result>/test2.jsp</result>
        </action>   
    </package>

    <package name="example" extends="json-default">

        <action name="ajaxHandler" class="com.sesoft.test.AjaxHandler">
            <result name="success" type="json" />
        </action>

    </package>
</struts>

```

Before I added the json Action, all other action performs fine. But after I added the json Action, the server failed to action with error code 503.

libs I've added "jsonplugin-0.33.jar" to the lib directory.