title: Getting empty value with dot walk for groupBy in GlideAggrigate
body: <p>I need to get the value for classname in below case. I am getting empty value. Let me know what I am missing. I need to find all distinct classes for every type.</p>
  
  <pre><code>var ga_type = new GlideAggregate('cmdb_rel_ci');
  ga_type.groupBy('type');
  ga_type.query();
  
  if(ga_type.next()){
      gs.log("Type : " + ga_type.type.getValue());
  
      var ga_parent = new GlideAggregate('cmdb_rel_ci');
      ga_parent.addQuery('type.sys_id', ga_type.type.getValue());
      ga_parent.groupBy('parent.sys_class_name');
      ga_parent.query();
  
      var parent = [];
      while(ga_parent.next()){
          var p = {};
          p.parentClassName = ga_parent.parent.sys_class_name.toString();
          p.parentName = ga_parent.parent.name.toString();
          gs.log("ParentClassName : " + p.parentClassName + " Parent Name : " + p.parentName);
          parent.push(p);
      }
  }
  </code></pre>