import java.util.List;

import org.apache.maven.project.MavenProject;

/**
 * Describes the interdependencies between projects in the reactor.
 *
 * @since 3.0-alpha
 */
public interface ProjectDependencyGraph {

    /**
     * Gets all collected projects.
     *
     * @return All collected projects.
     *
     * @since 3.5.0
     */
    List<MavenProject> getAllProjects();

    /**

    private volatile boolean halted = false;

    public ReactorBuildStatus(ProjectDependencyGraph projectDependencyGraph) {
        this.projectDependencyGraph = projectDependencyGraph;
    }

    public boolean isBlackListed(MavenProject project) {
        return blackListedProjects.contains(BuilderCommon.getKey(project));
    }

    public void blackList(MavenProject project) {

        if (activeProjects.size() != projectDependencyGraph.getSortedProjects().size()) {
            projectDependencyGraph = new FilteredProjectDependencyGraph(projectDependencyGraph, activeProjects);
        }

        return Result.success(projectDependencyGraph);
    }

    private List<MavenProject> trimProjectsToRequest(

import java.util.Map;
import java.util.Objects;

import org.apache.maven.execution.ProjectDependencyGraph;
import org.apache.maven.project.MavenProject;

/**
 * Provides a sub view of another dependency graph.
 *
 */
class FilteredProjectDependencyGraph implements ProjectDependencyGraph {

    private ProjectDependencyGraph projectDependencyGraph;

    private Map<MavenProject, ?> whiteList;

    private final ProjectBuildList projectBuilds;

    private final ProjectDependencyGraph projectDependencyGraph;

    private final Set<MavenProject> finishedProjects = new HashSet<>();

    public ConcurrencyDependencyGraph(ProjectBuildList projectBuilds, ProjectDependencyGraph projectDependencyGraph) {
        this.projectDependencyGraph = projectDependencyGraph;
        this.projectBuilds = projectBuilds;
    }

import org.apache.maven.execution.ProjectDependencyGraph;
import org.apache.maven.model.building.Result;

/**
 * Builds the {@link ProjectDependencyGraph inter-dependencies graph} between projects in the reactor.
 *
 * @since 3.0-alpha
 */
public interface GraphBuilder {
    String HINT = "graphBuilder";

    Result<? extends ProjectDependencyGraph> build(MavenSession session);

        ProjectDependencyGraph graph = threeProjectsDependingOnASingle();
        final List<MavenProject> downstreamProjects = graph.getUpstreamProjects(depender1, true);
        assertEquals(aProject, downstreamProjects.get(0));
    }

    private ProjectDependencyGraph threeProjectsDependingOnASingle()

            }
        }

        if (!graphResult.hasErrors()) {
            ProjectDependencyGraph projectDependencyGraph = graphResult.get();
            session.setProjects(projectDependencyGraph.getSortedProjects());
            session.setAllProjects(projectDependencyGraph.getAllProjects());
            session.setProjectDependencyGraph(projectDependencyGraph);
        }

        return graphResult;
    }

    @Deprecated

 * under the License.
 */
package org.apache.maven.lifecycle.internal;

import java.util.List;

import org.apache.maven.execution.MavenSession;
import org.apache.maven.execution.ProjectDependencyGraph;
import org.apache.maven.project.MavenProject;

/**
 * A build context that matches a Maven project to a given task segment, and the session to be used.
 * <p>
 * A note to the reader;
 * </p>
 * <p>

                ProjectDependencyGraphStub.getProjectBuildList(ProjectDependencyGraphStub.getMavenSession());

        ProjectDependencyGraph projectDependencyGraph = new ProjectDependencyGraphStub();

        ConcurrencyDependencyGraph graph = new ConcurrencyDependencyGraph(projectBuildList, projectDependencyGraph);

        // start
        assertEquals(0, graph.getFinishedProjects().size());