code: public FieldCounter<Double> extract(String jsonString, String recordId) {
      return extract(jsonString, recordId, false);
    }
docs: Extracts sums and average of TF-IDF value for the schema's Solr field array
  without collecting the terms.
  
  @param jsonString
  The JSON string
  @param recordId
  The record identifier
  @return
  Sums and average of TF-IDF value