title: wso2 esb filter with xquery expression inside property
body: <p>I want to use this expression in WSO2 property mediator </p>
  
  <pre><code>sum(//datas//queryResponse[CODEAGENCE='01003']//NOMBER)
  </code></pre>
  
  <p>I have done this to count without apply filter</p>
  
  <pre><code>fn:sum($ctx:datas//*[local-name()='queryResponse']//*[local-name()='NOMBRE'])
  </code></pre>