}

    public List<MetadataGraphEdge> getIncidentEdges(MetadataGraphVertex vertex) {
        checkEdges();
        return incidentEdges.get(vertex);
    }

    public List<MetadataGraphEdge> getExcidentEdges(MetadataGraphVertex vertex) {
        checkEdges();
        return excidentEdges.get(vertex);
    }

    public boolean isVersionedVertices() {
        return versionedVertices;
    }