title: How to retrieve Solr documents having at least 2 numFound with grouping
body: <p>I'm working with Solr and grouping (field collapsing) function.</p>
  
  <p>The request I want to do is the following : get only documents having the "rating" field, and having <strong>at least</strong> 2 documents in the result[@name='doclist'] node.</p>
  
  <p>The request :</p>
  
  <pre><code>/select/?q=rating:[* TO *]&amp;version=2.2&amp;start=0&amp;rows=10&amp;indent=on&amp;group=true&amp;group.field=HashKey&amp;group.ngroups=true
  </code></pre>
  
  <p>Is there a way to do that?</p>