title: How to filter by property components with searchable?
body: <p>i have two domain class like this :</p>
  
  <pre><code>class ExhibitionPrint {
    Exhibition exhibition
    Print print
  
    String title
    String description
    ....
  
  
    static searchable = {
        printSizes    component: true
        exhibition    component: true
  }
  }
  </code></pre>
  
  <p>And </p>
  
  <pre><code>class Exhibition {
  
  String title
  boolean isPublished
      ....
  static hasMany = [exhibitionPrints: ExhibitionPrint]
  
  static searchable = {  
      exhibitionPrints component: true
  }
  }
  </code></pre>
  
  <p>I used a closure in the search but it doesn't seem to work, I get results even when exhibition.isPublished is equal to false.
   I have something like this: </p>
  
  <pre><code>def searchResult = ExhibitionPrint.search{
  must{
           queryString(query)
           term("ExhibitionPrint.exhibition.isPublished", true)
  }
  }.results
  </code></pre>
  
  <p>Any idea how to implement this?</p>