vr.prototype = groupbyprototype;
vr.prototype = groupbyPrototype;
    Relation getGroupbySubnodeRelation () {	if (groupby == null)	    throw new RuntimeException ("getGroupbySubnodeRelation called on non-group-by relation");	Relation vr = new Relation (this);	vr.order = order;	vr.prototype = groupbyprototype;	vr.filter = filter;	vr.constraints = constraints;	vr.addConstraint (new Constraint (null, null, groupby, true));	vr.aggressiveLoading = aggressiveLoading;	vr.aggressiveCaching = aggressiveCaching;	return vr;    }