code: @Override
    public boolean visit(final Node nodeFrom, final Node nodeTo) {
      if (!nodeFrom.getName().isEmpty()) {
        this.graphStr
            .append("  ")
            .append(nodeFrom.getName())
            .append(" -> ")
            .append(nodeTo.getName())
            .append(" [style=solid, dir=back, arrowtail=diamond];\n");
      }
      return true;
    }
docs: Process current edge of the configuration graph.
  
  @param nodeFrom Current configuration node.
  @param nodeTo   Destination configuration node.
  @return true to proceed with the next node, false to cancel.