title: EL conditional render based on composite component attribute
body: <p>I have a composite component on which I have a parameter that I would like to add only depending on an attribute. I've tried to do this but the parameter is always being added.</p>
  
  <pre><code>&lt;cc:interface&gt;
      &lt;cc:attribute name="testParam" default="#{null}"/&gt;
  &lt;/cc:interface&gt;
  &lt;!-- IMPLEMENTATION --&gt;
  &lt;cc:implementation&gt;
          &lt;p:commandLink id="nav-link" value="TESTLINK"
                         process="@this"update="@form &gt;
              &lt;f:param id="test1" name="test1" 
                 value="#{cc.attrs.testParam}"
                 rendered="#{cc.attrs.testParam ne null}"/&gt;
              &lt;/p:commandLink&gt;
              &lt;f:param id="test2" name="test2" 
                 value="#{cc.attrs.testParam}"
                 rendered="#{cc.attrs.testParam eq 'null' ? false : true}"/&gt;
              &lt;/p:commandLink&gt;
              &lt;f:param id="test3" name="test3" 
                 value="#{cc.attrs.testParam}"
                 rendered="#{cc.attrs.testParam ne 'null'}"/&gt;
              &lt;/p:commandLink&gt;
      &lt;/cc:implementation&gt;
  </code></pre>
  
  <p>For every case, the parameter is being added with string value 'null'. Any hints?</p>
  
  <p>Thanks!</p>