code: func (fs *TermvectorsFilterSettings) Source() (interface{}, error) {
  	source := make(map[string]interface{})
  	if fs.maxNumTerms != nil {
  		source["max_num_terms"] = *fs.maxNumTerms
  	}
  	if fs.minTermFreq != nil {
  		source["min_term_freq"] = *fs.minTermFreq
  	}
  	if fs.maxTermFreq != nil {
  		source["max_term_freq"] = *fs.maxTermFreq
  	}
  	if fs.minDocFreq != nil {
  		source["min_doc_freq"] = *fs.minDocFreq
  	}
  	if fs.maxDocFreq != nil {
  		source["max_doc_freq"] = *fs.maxDocFreq
  	}
  	if fs.minWordLength != nil {
  		source["min_word_length"] = *fs.minWordLength
  	}
  	if fs.maxWordLength != nil {
  		source["max_word_length"] = *fs.maxWordLength
  	}
  	return source, nil
  }
docs: // Source returns JSON for the query.