title: How do I conditionally render an <f:facet>?
body: <p>I would like to be able to conditionally omit a footer from a PrimeFaces panel element:</p>
  
  <pre><code>&lt;p:panel header="some text"&gt;
      &lt;f:facet name="footer"&gt;
          #{message}
      &lt;/f:facet&gt;
      &lt;!-- ... --&gt;
  &lt;/p:panel&gt;
  </code></pre>
  
  <p>I hoped that the <code>rendered</code> attribute would work:</p>
  
  <pre><code>&lt;p:panel header="some text"&gt;
      &lt;f:facet name="footer" rendered="#{!empty message}"&gt;
          #{message}
      &lt;/f:facet&gt;
      &lt;!-- ... --&gt;
  &lt;/p:panel&gt;
  </code></pre>
  
  <p>But the footer is still rendered, with empty content. It appears that <code>facet</code> does not have the <code>rendered</code> attribute: <a href="http://www.jsftoolbox.com/documentation/help/12-TagReference/core/f_facet.html">http://www.jsftoolbox.com/documentation/help/12-TagReference/core/f_facet.html</a>.</p>
  
  <p><strong>What's the right way to do this?</strong></p>