title: null check in jsf expression language
body: <p>Please see this Expression Language</p>
  
  <pre><code>styleClass="#{obj.validationErrorMap eq null ? ' ' :  
       obj.validationErrorMap.contains('key')?'highlight_field':'highlight_row'}"
  </code></pre>
  
  <p>Even if the map is null, <code>highlight_row</code> style is getting applied.</p>
  
  <p>So I changed to </p>
  
  <pre><code>styleClass="#{empty obj.validationErrorMap ? ' ' :  
       obj.validationErrorMap.contains('key')?'highlight_field':'highlight_row'}"
  </code></pre>
  
  <p>Even then, <code>highlight_row</code> is getting applied.<br>
  if the map is <code>empty OR null</code> I dont want any style  to be applied.</p>
  
  <p>Any help? and reasons for this behaviour? </p>