title: JSF h:panelGroup inside f:facet does not work
body: <p>I have extracted this problem out into a simple scenario. obviously I can work around the issue, but curious as to what the explanation might be, and why this does not work.</p>
  
  <p>using h:dataTable as an example, if I put a <code>&lt;h:panelGroup&gt;</code> inside one of the <code>&lt;f:facet&gt;</code>'s of the table, whats inside the <code>&lt;h:panelGroup&gt;</code> does not get displayed, and I dont see why.</p>
  
  <p>this is in a project using Spring, Hibernate and Primefaces with JSF2 and facelets, running on Tomcat, but this appears to be stock standard JSF behaviour?</p>
  
  <p>In the example below, the contents of both h:panelGroup do not get displayed, unless I put an element before the h:panelGroup (for example some text) then it does get displayed?</p>
  
  <pre><code>    &lt;!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"&gt;
  &lt;html xmlns="http://www.w3.org/1999/xhtml"
        xmlns:h="http://java.sun.com/jsf/html"
        xmlns:f="http://java.sun.com/jsf/core"&gt;
  
  &lt;f:view contentType="text/html"&gt;
      &lt;h:head&gt;
          &lt;f:facet name="first"&gt;
              &lt;meta http-equiv="X-UA-Compatible" content="IE=edge"/&gt;
              &lt;meta content='text/html; charset=UTF-8' http-equiv="Content-Type"/&gt;
              &lt;title&gt;-- Nothing --&lt;/title&gt;
          &lt;/f:facet&gt;
  
      &lt;/h:head&gt;
  
      &lt;h:body&gt;
          &lt;h:form id="nothingForm"&gt;
          &lt;h:dataTable id="nothingData" value="#{null}" var="item"&gt;
             &lt;h:column&gt;
                 &lt;f:facet name="header"&gt; col1 &lt;/f:facet&gt;
                 things
             &lt;/h:column&gt;
              &lt;h:column&gt;
                  &lt;f:facet name="header"&gt;
                      &lt;h:panelGroup id="headerGroup" rendered="#{true}"&gt;
                      crappo
                      &lt;/h:panelGroup&gt;
                      col2
                  &lt;/f:facet&gt;
                  stuff
              &lt;/h:column&gt;
              &lt;f:facet name="footer"&gt;
                  &lt;h:panelGroup id="footerGroup" rendered="#{true}"&gt;
                      crappo
                      &lt;h:commandButton id="btn1" value="Button 1" /&gt;
                  &lt;/h:panelGroup&gt;
                  &lt;h:commandButton id="btn2" value="Button 2" /&gt;
              &lt;/f:facet&gt;
          &lt;/h:dataTable&gt;
          &lt;/h:form&gt;
      &lt;/h:body&gt;
  &lt;/f:view&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>thanks for looking!</p>