block12.

{
    ...
    "aggregations" : {
        "custom_field" : {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 0,
            "buckets" : [
                {
                    "key" : color,
                    "doc_count" : 6
                },
                {
                    "key" : animal,
                    "doc_count" : 3
                },
            ]
        }
    }
}