Path getRootDirectory();

    /**
     * Returns project parent project, if any.
     * <p>
     * Note that the model may have a parent defined, but an empty parent
     * project may be returned if the parent comes from a remote repository,
     * as a {@code Project} must refer to a buildable project.
     *
     * @return an optional containing the parent project
     * @see Model#getParent()
     */
    @Nonnull

        projects.add(project1);
        MavenProject project2 = createProject("groupId", "artifactId2", "1.0");
        projects.add(project2);
        project1.getDependencies().add(createDependency(project2));

        projects = new ProjectSorter(projects).getSortedProjects();

        assertEquals(project2, projects.get(0));
        assertEquals(project1, projects.get(1));
    }

    @Test

        MavenProject project = result.get(0).getProject();
        // verify a few typical parameters are not duplicated
        assertEquals(1, project.getTestCompileSourceRoots().size());
        assertEquals(1, project.getCompileSourceRoots().size());
        assertEquals(1, project.getMailingLists().size());
        assertEquals(1, project.getResources().size());
    }

    @Test

        MavenProject project = mock(MavenProject.class);
        when(project.getGroupId()).thenReturn("org.apache.maven.plugins.overflow");
        when(project.getArtifactId()).thenReturn("maven-project-info-reports-plugin");
        when(project.getPackaging()).thenReturn("maven-plugin");
        when(project.getName()).thenReturn("Apache Maven Project Info Reports Plugin");

    // Before the fix, this would return dProject and eProject twice, once from bProject and once from cProject. As
    // aProject is whitelisted, it should not be returned as a downstream project for itself. bProject and cProject
    // are not whitelisted, so they should return their downstream projects, both have dProject and eProject as

import org.apache.maven.project.CycleDetectedException;
import org.apache.maven.project.DuplicateProjectException;
import org.apache.maven.project.MavenProject;
import org.apache.maven.project.ProjectBuildingException;
import org.apache.maven.project.collector.MultiModuleCollectionStrategy;
import org.apache.maven.project.collector.PomlessCollectionStrategy;
import org.apache.maven.project.collector.RequestPomCollectionStrategy;

        initRepoSession(request, configuration);

        List<MavenProject> projects = new ArrayList<>();

        if (pom != null) {
            MavenProject project = projectBuilder.build(pom, configuration).getProject();

            projects.add(project);
            if (includeModules) {
                for (String module : project.getModules()) {
                    File modulePom = new File(pom.getParentFile(), module);

            if (projects != null) {
                Map<String, Map<String, Map<String, MavenProject>>> map = new HashMap<>();
                projects.forEach(project -> map.computeIfAbsent(project.getGroupId(), k -> new HashMap<>())
                        .computeIfAbsent(project.getArtifactId(), k -> new HashMap<>())
                        .put(project.getVersion(), project));
                this.projects = map;
            } else {

            if (isBom) {
                return buildBom(session, project, src);
            } else {
                return buildPom(session, project, src);
            }
        } else {
            return buildNonPom(session, project, src);
        }
    }

    protected Model buildPom(RepositorySystemSession session, MavenProject project, ModelSource src)
            throws ModelBuilderException {

    @Nonnull
    public Map<String, String> getProperties(@Nonnull Project project) {
        return Collections.unmodifiableMap(
                new PropertiesAsMap(getMavenProject(project).getProperties()));
    }

    @Override
    @Nonnull
    public Optional<Project> getExecutionProject(@Nonnull Project project) {
        // Session keep tracks of the Project per project id,