Index only specific data in elasticsearch from kafka input

[scireon]

I am using kafka as my input and put it in elasticsearch (output)

input {
    kafka {
        topics => ["maxwell"]
        codec => json
    }
}
filter {
}
output {
    stdout { codec => rubydebug }
    elasticsearch {
        index => 'test_kafka'
        document_type => "%{table}"
        hosts => 'localhost:9200'
    }
}

When this runs, it outputs the following json

{
  "database": "my_db",
  "xid": 88935,
  "@timestamp": "2016-11-14T12:00:13.763Z",
  "data": {
    "contact_country_code": null,
    "contact_type_id": 1,
    "created": "2014-10-03 12:24:36",
    "modified_by": null,
    "modified": "2014-10-03 12:24:36",
    "contact_id": 1,
    "is_default": 0,
    "created_by": null,
    "contact_number": "1241222232"
  },
  "old": {
    "contact_number": "1241222"
  },
  "commit": true,
  "@version": "1",
  "type": "update",
  "table": "contact",
  "ts": 1479124813
}

My question is, how can I only extract the data key with dynamic document_type in elasticsearch to achieve the this one

{
  "_index": "test_kafka",
  "_type": "contact",
  "_id": "AVhitY804rvpX8qdVt9d",
  "_score": 1,
  "_source": {
    "contact_country_code": null,
    "contact_type_id": 1,
    "created": "2014-10-03 12:24:36",
    "modified_by": null,
    "modified": "2014-10-03 12:24:36",
    "contact_id": 1,
    "is_default": 0,
    "created_by": null,
    "contact_number": "1241222232"
  }
}

[scireon]

Topic can be followed here. http://stackoverflow.com/questions/40600708/logstash-index-only-specific-data-in-elasticsearch-from-kafka-input/40602386#40602386