code: @SuppressWarnings("unchecked")
    public <T extends Indexer> T getIndexer(Class<T> indexerClass) {
      Indexer indexer = cache.get(indexerClass);
      if (indexer == null) {
        indexer = createIndexer(indexerClass);
      }
      return (T) indexer;
    }
docs: Returns the {@link Indexer} of the given implementation class.
  
  @param indexerClass
  the implementation class of the Indexer interface
  @return the Indexer