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);

     * @param coordinate coordinates of the artifact to resolve
     * @return requested artifact together with the path to its file
     * @throws org.apache.maven.api.services.ArtifactResolverException if the artifact resolution failed
     *
     * @see org.apache.maven.api.services.ArtifactResolver#resolve(Session, Collection)
     */
    @Nonnull
    Map.Entry<Artifact, Path> resolveArtifact(@Nonnull ArtifactCoordinate coordinate);

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;

  private final ImmutableList<Service> services;

  /**
   * Constructs a new instance for managing the given services.
   *
   * @param services The services to manage
   * @throws IllegalArgumentException if not all services are {@linkplain State#NEW new} or if there
   *     are any duplicate services.
   */
  public ServiceManager(Iterable<? extends Service> services) {

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 org.apache.maven.api.model.Profile;
import org.apache.maven.api.services.ArtifactManager;
import org.apache.maven.api.services.LifecycleRegistry;
import org.apache.maven.api.services.Lookup;
import org.apache.maven.api.services.MavenException;
import org.apache.maven.api.services.PackagingRegistry;
import org.apache.maven.api.services.RepositoryFactory;
import org.apache.maven.api.services.SettingsBuilder;
import org.apache.maven.api.services.TypeRegistry;

import java.util.stream.Collectors;

import org.apache.maven.api.*;
import org.apache.maven.api.services.DependencyResolver;
import org.apache.maven.api.services.DependencyResolverResult;
import org.apache.maven.api.services.ProjectBuilder;
import org.apache.maven.api.services.ProjectBuilderRequest;
import org.apache.maven.api.services.SettingsBuilder;
import org.apache.maven.artifact.handler.manager.ArtifactHandlerManager;

Once the config changes are applied, proceed to restart **Hadoop** services.

![hdfs-services](https://github.com/minio/minio/blob/master/docs/bigdata/images/image7.png?raw=true "hdfs restart services")

### **3.2 Configure Spark2**

Navigate to **Services** -> **Spark2** -> **CONFIGS** as shown below

   */
  public void testTransitionRace() throws TimeoutException {
    for (int k = 0; k < 1000; k++) {
      List<Service> services = Lists.newArrayList();
      for (int i = 0; i < 5; i++) {
        services.add(new SnappyShutdownService(i));
      }
      ServiceManager manager = new ServiceManager(services);
      manager.startAsync().awaitHealthy();
      manager.stopAsync().awaitStopped(10, TimeUnit.SECONDS);
    }
  }