title: Conditionally render component on presence of message from specific object
body: <p>I intend to verify a field <code>usernameTxt</code> in form with <strong>bootstrap</strong> below, with a reference to <a href="https://stackoverflow.com/a/18836757/5668956"><strong>BalusC</strong> answer</a> and <a href="https://stackoverflow.com/a/31738371/5668956"><strong>Aleksei Loginov</strong> answer</a></p>
  
  <pre><code>&lt;div class="form-group"&gt;
                  &lt;label class="control-label col-sm-2" for="usernameTxt"&gt;Fullname(*):&lt;/label&gt;
                  &lt;div class="col-sm-10"&gt;
                      &lt;h:inputText type="text" class="form-control" id="usernameTxt"
                          a:placeholder="Enter your name" required="true"
                          requiredMessage="Fullname is required"
                          value="#{data.personalInformation.username}"&gt;&lt;/h:inputText&gt;
                      &lt;h:panelGroup layout="block" rendered="#{not empty facesContext.getMessageList('usernameTxt')}" class="alert alert-danger"&gt;
                          &lt;h:message for="usernameTxt"&gt;&lt;/h:message&gt;
                      &lt;/h:panelGroup&gt;
                  &lt;/div&gt;
              &lt;/div&gt;
  </code></pre>
  
  <p>The wish is that if the input text is empty then it will render the block <code>&lt;h:panelGroup&gt;</code>, and the result should be like 
  <a href="https://i.stack.imgur.com/tiJij.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tiJij.png" alt="enter image description here"></a></p>
  
  <p>(That photo is when I remove the <code>not</code> condition in the <code>rendered</code> property). I can't make the block rendered conditionally correctly. Is there any syntax in the render condition, or am I missing something here ? </p>