title: Expression to filter out elements with empty arrays using `jsonPath`
body: <p>I have a JSON payload of the form: </p>
  
  <pre><code>[
    {"id": 1, "list": [1], "name":"one"}, 
    {"id": 2, "list": [1,2], "name":"two"},
    {"id": 3, "list": [], "name":"three"}
  ]
  </code></pre>
  
  <p>And I want to filter out the element from the array the contains an empty <code>"list"</code> property.  In other words, I want to discard the element with <code>id=3</code> and process only the first and second element in my example above.</p>
  
  <p>Currently, my filter looks like this:</p>
  
  <pre><code>&lt;!-- ne == not equals --&gt;
  &lt;int:filter id="filter" 
              input-channel="in" 
              output-channel="out" 
              expression="#jsonPath(payload, '$[*].list') ne '[]'"
              discard-channel="consoleOutputChannel" /&gt;
  </code></pre>
  
  <p>But this is not working, how should I indicate to my <code>expression</code> that I want to exclude elements with empty <code>list</code> properties?</p>