title: geoserver cross-layer cql filter with feature id
body: <p>I want to get the features of layer A that have intersection with a specific feature in layer B (using the id of the feature in layer B). below is my query:</p>
  
  <pre><code>localhost:8080/geoserver/wms?LAYERS=sf:roads,sf:restricted,sf:bugsites&amp;STYLES=&amp;FORMAT=image/png&amp;SERVICE=WMS&amp;VERSION=1.1.1&amp;REQUEST=GetMap&amp;EXCEPTIONS=application/vnd.ogc.se_inimage&amp;SRS=EPSG:26713&amp;CQL_FILTER=INCLUDE;INCLUDE;INTERSECTS(the_geom, querySingle('sf:restricted', 'the_geom','IN('restricted.4')'))&amp;BBOX=589081.6705629,4914128.1213261,609174.02430924,4928177.0717971&amp;WIDTH=512&amp;HEIGHT=358
  </code></pre>
  
  <p>but the query cannot be parsed and I receive this error:
  <a href="https://i.stack.imgur.com/wPGf7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wPGf7.png" alt="enter image description here"></a></p>