VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);
    }

    public Collection<Vertex> getVertices() {
        return vertices.values();
    }

    Vertex addVertex(String label) {
        return vertices.computeIfAbsent(label, Vertex::new);
    }

        assertNotNull(res, "null graph after resolver");
        assertNotNull(res.getVertices(), "no vertices in the resulting graph after resolver");

        assertNotNull(res.getExcidentEdges(v1), "no edges in the resulting graph after resolver");

        assertEquals(4, res.getVertices().size(), "wrong # of vertices in the resulting graph after resolver");
        assertEquals(
                2,

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

        checkEdges(nE);
    }

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

    private void checkVertices(int nVertices) {
        if (vertices == null) {
            vertices = new TreeSet<>();
        }
    }

    private void checkEdges() {

        String projectKey = ArtifactUtils.versionlessKey(groupId, artifactId);

        Map<String, Vertex> vertices = vertexMap.get(projectKey);

        if (vertices != null) {
            if (isSpecificVersion(version)) {
                Vertex vertex = vertices.get(version);
                if (vertex != null) {
                    addEdge(projectVertex, vertex, project, projectMap, force, safe);

        }

        if (graph.isEmptyEdges()) {
            return null; // no edges - nothing to worry about
        }

        final TreeSet<MetadataGraphVertex> vertices = graph.getVertices();

        try {
            // edge case - single vertex graph
            if (vertices.size() == 1) {
                return new MetadataGraph(entry);

        VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);
    }

    public Collection<Vertex> getVertices() {
        return vertices.values();
    }

    Vertex addVertex(String label) {
        return vertices.computeIfAbsent(label, Vertex::new);
    }

import org.apache.maven.api.services.ModelBuilderException;
import org.apache.maven.api.services.ModelBuilderRequest;
import org.apache.maven.api.services.ModelBuilderResult;
import org.apache.maven.api.services.ModelProblemCollector;
import org.apache.maven.api.services.ModelSource;
import org.apache.maven.api.services.ModelTransformer;
import org.apache.maven.api.services.SuperPomProvider;

import org.apache.maven.api.di.Named;
import org.apache.maven.api.services.BuilderProblem;
import org.apache.maven.api.services.SettingsBuilder;
import org.apache.maven.api.services.SettingsBuilderException;
import org.apache.maven.api.services.SettingsBuilderRequest;
import org.apache.maven.api.services.SettingsBuilderResult;
import org.apache.maven.api.services.Source;
import org.apache.maven.api.services.xml.SettingsXmlFactory;

import java.io.Writer;

import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.services.xml.SettingsXmlFactory;
import org.apache.maven.api.services.xml.XmlReaderException;
import org.apache.maven.api.services.xml.XmlReaderRequest;
import org.apache.maven.api.services.xml.XmlWriterException;
import org.apache.maven.api.services.xml.XmlWriterRequest;
import org.apache.maven.api.settings.InputSource;

import org.apache.maven.api.services.ModelBuilderException;
import org.apache.maven.api.services.ModelBuilderRequest;
import org.apache.maven.api.services.ModelProblem;
import org.apache.maven.api.services.ModelProblemCollector;
import org.apache.maven.api.services.ModelSource;
import org.apache.maven.api.services.ModelTransformerContext;
import org.apache.maven.api.services.ModelTransformerContextBuilder;