var response = Client.Search<myclass>(s => s
                                     .Type("type")
                                      .Aggregations(a => a
                                        .Terms("code_bucket", t => t
                                         .Field("field_of_aggregation")
                                         .Size(30)
                                         .Order(TermsOrder.CountAscending)
                                         .Aggregations(a2 => a2
                                         .TopHits("code_bucket_top_hits", th => th.Size(20))
                                       )
                                       )));

var firstBucket= response.Aggs.Terms("code_bucket");
foreach (var bucket in firstBucket.Buckets)
            {
                var hits = bucket.TopHits("code_bucket_top_hits");
                foreach (var hit in hits.Documents<myclass>())
                {
                    var prop1= hit.prop1;
                    var prop2= hit.prop2;
                }
            }
   }