code: private void initializeSecondaryIndexer() {
      SecondaryIndex secondaryIndexAnnotation = field.getAnnotation(SecondaryIndex.class);
      if (secondaryIndexAnnotation == null) {
        return;
      }
      String indexName = secondaryIndexAnnotation.name();
      if (indexName == null || indexName.trim().length() == 0) {
        indexName = DEFAULT_SECONDARY_INDEX_PREFIX + mappedName;
      }
      this.secondaryIndexName = indexName;
      try {
        secondaryIndexer = IndexerFactory.getInstance().getIndexer(field);
      } catch (Exception exp) {
        String pattern = "No suitable Indexer found or error occurred while creating the indexer "
            + "for field %s in class %s";
        String message = String.format(pattern, field.getName(), field.getDeclaringClass().getName());
        throw new EntityManagerException(message, exp);
      }
  
    }
docs: Initializes the secondary indexer for this property, if any.