code: func (r *SearchRequest) SearchSource(searchSource *SearchSource) *SearchRequest {
  	if searchSource == nil {
  		r.searchSource = NewSearchSource()
  		return r
  	}
  	r.searchSource = searchSource
  	return r
  }
docs: // SearchSource allows passing your own SearchSource, overriding
  // all values set on the request (except Source).