title: empty EL expression on JSF datatable var attribute's field always false
body: <p>I have the following EL expression which references a property on the var attribute:</p>
  
  <p><code>empty _item.addressLine1</code></p>
  
  <p><code>addressLine1</code> is a String property on the Address bean, which is accessed via the <code>personBean.person.addresses</code> property which returns a <code>Set&lt;Address&gt;</code>.</p>
  
  <p>Here is the EL expression in context:</p>
  
  <pre><code>&lt;h:dataTable id="personBeanPersonAddresses" styleClass="data-table" value="#{forgeview:asList(personBean.person.addresses)}" var="_item"&gt;
      &lt;h:column&gt;
          &lt;f:facet name="header"&gt;
              &lt;h:outputText value="Address Line 1"/&gt;
          &lt;/f:facet&gt;
          &lt;h:link outcome="/address/view"&gt;
              &lt;f:param name="id" value="#{_item.id}"/&gt;
  
              &lt;h:panelGroup rendered="#{!empty _item.addressLine1}"&gt;
                  &lt;h:outputText id="itemAddressLine1" value="#{_item.addressLine1}"/&gt;&lt;br/&gt;
              &lt;/h:panelGroup&gt;
          &lt;/h:link&gt;
      &lt;/h:column&gt;
      ....
  </code></pre>
  
  <p>The problem is the expression always returns false, regardless of whether addressLine1 is the empty string or not. As if to confirm this, The facelet Validator in Eclipse produces the following warning:</p>
  
  <blockquote>
    <p>This empty expression always evaluates to false.  Only string, maps,
    arrays and collection have meaningful values for the empty operator</p>
  </blockquote>
  
  <p>But I'm not sure how to fix this. I'm running JBoss AS 7.1 with jboss-el-api_2.2_spec-1.0.0.Final</p>