初试es6.5.4的composite出错

GET /_search

{

    "aggs" : {

        "my_buckets": {

            "composite" : {

                "size": 2,

                 "sources" : [

                    { "date": { "date_histogram": { "field": "timestamp", "interval": "1d", "order": "desc" } } },

                    { "product": { "terms": {"field": "product", "order": "asc" } } }

                ],

                "after": { "date": 1494288000000, "product": "mad max" } 

            }

        }

    }

}