func (a *SumBucketAggregation) SubAggregation(name string, subAggregation Aggregation) *SumBucketAggregation {
	a.subAggregations[name] = subAggregation
	return a
}
SubAggregation adds a sub-aggregation to this aggregation.
package elastic
type SumBucketAggregation struct {
	format    string
	gapPolicy string
	subAggregations map[string]Aggregation
	meta            map[string]interface{}
	bucketsPaths    []string
}
func NewSumBucketAggregation() *SumBucketAggregation {
	return &SumBucketAggregation{
		subAggregations: make(map[string]Aggregation),
		bucketsPaths:    make([]string, 0),
	}
}
func (a *SumBucketAggregation) Format(format string) *SumBucketAggregation {
	a.format = format
	return a
}
func (a *SumBucketAggregation) GapPolicy(gapPolicy string) *SumBucketAggregation {
	a.gapPolicy = gapPolicy
	return a
}
func (a *SumBucketAggregation) GapInsertZeros() *SumBucketAggregation {
	a.gapPolicy = "insert_zeros"
	return a
}
func (a *SumBucketAggregation) GapSkip() *SumBucketAggregation {
	a.gapPolicy = "skip"
	return a
}