int nV = nVertices;
        if (nVertices < 1) {
            nV = 1;
        }

        checkVertices(nV);

        int nE = nVertices;
        if (nEdges <= nV) {
            nE = 2 * nE;
        }

        checkEdges(nE);
    }

    private void checkVertices() {
        checkVertices(DEFAULT_VERTICES);
    }

    private void checkVertices(int nVertices) {

                            .path(modelSource.getPath())
                            .inputStream(is)
                            .build());
                } catch (XmlReaderException ne) {
                    // still unreadable even in non-strict mode, rethrow original error
                    throw e;
                }