code: @Override
      public AtlasGraphIndex getGraphIndex(String indexName) {
          TitanGraphIndex index = management.getGraphIndex(indexName);
          return GraphDbObjectFactory.createGraphIndex(index);
      }
docs: /*
  (non-Javadoc)
  
  @see
  org.apache.atlas.repository.graphdb.AtlasGraphManagement#getGraphIndex(
  java.lang.String)