code: func (r *ReindexSource) FetchSourceIncludeExclude(include, exclude []string) *ReindexSource {
  	r.request = r.request.FetchSourceIncludeExclude(include, exclude)
  	return r
  }
docs: // FetchSourceIncludeExclude specifies that _source should be returned
  // with each hit, where "include" and "exclude" serve as a simple wildcard
  // matcher that gets applied to its fields
  // (e.g. include := []string{"obj1.*","obj2.*"}, exclude := []string{"description.*"}).