json-customize/src/main/resources/struts.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.5//EN"
    "https://struts.apache.org/dtds/struts-2.5.dtd">
<struts>
  <constant name="struts.enable.DynamicMethodInvocation" value="false"/>
  <constant name="struts.devMode" value="true"/>

  <bean type="org.apache.struts2.json.JSONWriter" name="flexJSONWriter" class="org.demo.FlexJSONWriter"
        scope="prototype"/>
  <constant name="struts.json.writer" value="flexJSONWriter"/>
  <constant name="struts.json.dateformat" value="MM/dd/yyyy"/>

  <package name="default" namespace="/" extends="json-default">

    <default-action-ref name="index"/>

    <action name="index">
      <result>/WEB-INF/index.jsp</result>
    </action>

    <action name="produce" class="org.demo.ProduceAction">
      <result type="json">
        <param name="includeProperties">addresses</param>
        <param name="excludeProperties">addresses.state</param>
        <param name="excludeNullProperties">true</param>
        <param name="root">user</param>
      </result>
    </action>

  </package>

  <!-- Add addition packages and configuration here. -->
</struts>