Struts2 tag for checking empty bean

<s:if test="%{!nmap.isEmpty()}">
 <thead>
   <tr>
     <td>Name</td>
     <td>Age</td>
   </tr>
 </thead>
</s:if>
 <tbody>
 <s:iterator var="Person" value="value">
 .
 .
 .
 </s:iterator>
 </tbody>