code: @Override
    public void addChange(DiffEntry change) {
      Path path = new Path(change.getNewPath());
      if (path.depth() == NODE_FILE_DEPTH) {
        addDataNode(change);
      } else if (path.depth() == EDGE_FILE_DEPTH) {
        addFlowEdge(change);
      }
    }
docs: Add an element (i.e., a {@link DataNode}, or a {@link FlowEdge} to
  the {@link FlowGraph} for an added, updated or modified node or edge file.
  @param change