anchor.diff:      ...
       "aggregations": {
           "my_buckets": {
  -            "after_key": { <1>
  +            "after_key": {
                   "date": 1494288000000,
                   "product": "mad max"
               },
  
positive.code: --------------------------------------------------
  
  <1> Should restrict the aggregation to buckets that sort **after** the provided values.
  
  ==== Early termination
  
  
negative.code: --------------------------------------------------
  // TESTRESPONSE[s/\.\.\.//]
  
  To get the next set of buckets, resend the same aggregation with the `after`
  parameter set to the `after_key` value returned in the response.
  For example, this request uses the `after_key` value provided in the previous response:
  
  [source,console,id=composite-aggregation-after-example]
  --------------------------------------------------
  