private SimilarityMetric createEsaSimilarity(String name)
     throws ConfigurationException, IOException {
   JSONObject params = configuration.getMetric(name);
   ESASimilarity metric =
       new ESASimilarity(loadMainMapper(), loadIndex(requireString(params, "lucene")));
   if (params.containsKey("textLucene")) {
     metric.setTextHelper(loadIndex(requireString(params, "textLucene")));
   }
   return metric;
 }