If the value returned by the get method is an object, then the property tag will cause Struts 2 to call the object's toString method. Of course, you should always override Class Object's toString method in your model classes. Add the following toString method to the MessageStore class:
http://struts.apache.org/release/2.3.x/docs/using-struts-2-tags.html
Struts 2 property tag