WW-2482:

Fix Freemarker exception when model list entry has null value field

git-svn-id: https://svn.apache.org/repos/asf/struts/struts2/branches/STRUTS_2_0_X@620838 13f79535-47bb-0310-9956-ffa450edef68

core/src/main/resources/template/simple/checkboxlist.ftl

@@ -30,7 +30,7 @@
             <#assign itemKey = stack.findValue('top')/>
         </#if>
         <#if parameters.listValue?exists>
-            <#assign itemValue = stack.findString(parameters.listValue)/>
+            <#assign itemValue = stack.findString(parameters.listValue)?default("")/>
         <#else>
             <#assign itemValue = stack.findString('top')/>
         </#if>
@@ -52,4 +52,4 @@
     </@s.iterator>
 <#else>
   &nbsp;
-</#if>
+</#if>

core/src/test/java/org/apache/struts2/views/jsp/ui/CheckboxListTest.java

@@ -140,7 +140,8 @@ public class CheckboxListTest extends AbstractUITagTest {
         testAction.setFoo("hello");
         testAction.setList(new String[][]{
                 {"hello", "world"},
-                {"foo", "bar"}
+                {"foo", "bar"},
+                {"baz", null}
         });
 
         CheckboxListTag tag = new CheckboxListTag();

core/src/test/resources/org/apache/struts2/views/jsp/ui/CheckboxList-1.txt

@@ -5,5 +5,7 @@
 <label for="foo-1" class="checkboxLabel">world</label>
 <input type="checkbox" name="foo" value="foo" id="foo-2" title="mytitle" onchange="alert('foo');"/>
 <label for="foo-2" class="checkboxLabel">bar</label>
+<input type="checkbox" name="foo" value="baz" id="foo-3" title="mytitle" onchange="alert('foo');"/>
+<label for="foo-3" class="checkboxLabel"></label>
     </td>
 </tr>