Child - top hit aggregation highlights not working

[dpalaka (Despoina Palaka)]

Hi all,
I have used highlights in top hits aggregation successfully, but when I try it in a child-top hit aggregation it doesn't work. This is how my aggregation looks like:

---

"aggregations":{"group1" : {
  "terms" : {
    "field" : "property_1",
    "size" : 2
  },
 "aggregations" : {
    "group2" : {
      "terms" : {
        "field" : "property_2",
        "size" : 2
      },
      "aggregations" : {
        "child_group" : {
          "children" : {
            "type" : "child_type"
          },
          "aggregations" : {
            "children_filter" : {
              "filter" : {
                "bool" : {
                  "should" : [ {
                    "query_string" : {
                      "query" : "foo",
                      "default_field" : "value",
                      "allow_leading_wildcard" : true,
                      "lowercase_expanded_terms" : false
                    }
                  }, {
                    "query_string" : {
                      "query" : "foo",
                      "default_field" : "content",
                      "allow_leading_wildcard" : true,
                      "lowercase_expanded_terms" : false
                    }
                  } ],
                  "minimum_should_match" : "1"
                }
              },
              "aggregations" : {
                "top_hits1" : {
                  "top_hits" : {
                    "size" : 2,
                    "highlight" : {
                      "pre_tags" : [ "<strong>" ],
                      "post_tags" : [ "</strong>" ],
                      "fields" : {
                        "value" : {
                          "fragment_size" : 100,
                          "number_of_fragments" : 2,
                          "type" : "fvh",
                          "matched_fields" : [ "value" ]
                        },
                         "content" : {
                          "fragment_size" : 100,
                          "number_of_fragments" : 2,
                          "type" : "fvh",
                          "matched_fields" : [ "content" ]
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

Any suggestions?