IBucketSortAggregation
A parent pipeline aggregation which sorts the buckets of its parent multi-bucket aggregation.
Zero or more sort fields may be specified together with the corresponding sort order.
Each bucket may be sorted based on its _key, _count or its sub-aggregations.
In addition, parameters from and size may be set in order to truncate the result buckets.
Buckets in positions prior to the set value will be truncated
The policy to apply when gaps are found in the data
The number of buckets to return. Defaults to all buckets of the parent aggregation
The list of fields to sort on