public Collection<GraphEdge> getRemovedEdges() {
      Set<GraphEdge> result = new HashSet<>();
      Set<GraphEdge> hidden = getHiddenEdges().getEdges();
      result.addAll(ContainerUtil.filter(hidden, graphEdge -> graphEdge.getType() != GraphEdgeType.DOTTED));
      result.addAll(ContainerUtil.intersection(hidden, myLinearGraph.getDottedEdges().getEdges()));
      result.removeAll(myLinearGraph.getHiddenEdges().getEdges());
      return result;
    }
public Collection<GraphEdge> getRemovedEdges()