public List<String> findVersions(Artifact artifact) {
        List<String> versions = getProjects()
                .getOrDefault(artifact.getGroupId(), Collections.emptyMap())
                .getOrDefault(artifact.getArtifactId(), Collections.emptyMap())
                .values()
                .stream()
                .map(MavenProject::getVersion)

                || artifact.getArtifactId().isEmpty()
                || artifact.getBaseVersion().toString().isEmpty()) {
            artifact = session.createProducedArtifact(
                    artifact.getGroupId().isEmpty() ? project.getGroupId() : artifact.getGroupId(),
                    artifact.getArtifactId().isEmpty() ? project.getArtifactId() : artifact.getArtifactId(),

    }

    private CoreExtensionEntry createExtension(CoreExtension extension, List<Artifact> artifacts) throws Exception {
        String realmId = "coreExtension>" + extension.getGroupId() + ":" + extension.getArtifactId() + ":"
                + extension.getVersion();
        final ClassRealm realm = classWorld.newRealm(realmId, null);
        Set<String> providedArtifacts = Collections.emptySet();

        when(artifact.getArtifactId()).thenReturn("myArtifact");
        when(artifact.getBaseVersion()).thenReturn(versionParser.parseVersion("1.0-SNAPSHOT"));
        projectManager.attachArtifact(project, artifact, artifactPath);

        // Verify that an exception is thrown when the artifactId differs
        when(artifact.getArtifactId()).thenReturn("anotherArtifact");

    }

    private CoreExtensionEntry createExtension(CoreExtension extension, List<Artifact> artifacts) throws Exception {
        String realmId = "coreExtension>" + extension.getGroupId() + ":" + extension.getArtifactId() + ":"
                + extension.getVersion();
        final ClassRealm realm = classWorld.newRealm(realmId, null);
        Set<String> providedArtifacts = Collections.emptySet();

        MavenProject project = new MavenProject(model);

        assertEquals("test-group", project.getGroupId(), "groupId proto-inheritance failed.");
        assertEquals("real-artifact", project.getArtifactId(), "artifactId is masked.");
        assertEquals("1000", project.getVersion(), "version proto-inheritance failed.");

        // draw the NPE.
        project.getId();
    }

    @Test

        Artifact pom = repositorySystem.createProjectArtifact("org.apache.maven.its", "missing", "0.1");
        MavenProject project = getProject(pom, true);

        assertNotNull(project.getArtifactId());

        assertNotNull(project.getRemoteArtifactRepositories());
        assertTrue(project.getRemoteArtifactRepositories().isEmpty());

        assertNotNull(project.getPluginArtifactRepositories());

                        parent,
                        null,
                        Sources.resolvedSource(
                                pomFile,
                                artifact.getGroupId() + ":" + artifact.getArtifactId() + ":" + artifact.getVersion()));
            }
        }

        List<ProjectBuildingResult> build(List<File> pomFiles, boolean recursive) throws ProjectBuildingException {

        List<ProjectBuildingResult> projectBuildingResults =
                createProjectBuildingResultMocks(Stream.of(projectParent, projectModuleD)
                        .collect(Collectors.toMap(MavenProject::getArtifactId, identity()))
                        .values());
        when(projectBuilder.build(anyList(), anyBoolean(), any(ProjectBuildingRequest.class)))
                .thenReturn(projectBuildingResults);

        return dependency.getGroupId() + ":" + dependency.getArtifactId() + ":"
                + dependency.getType().id() + ":" + dependency.getClassifier();
    }

    private static String getDependencyKey(Dependency dependency) {
        return dependency.getGroupId() + ":" + dependency.getArtifactId() + ":"
                + (dependency.getType() != null ? dependency.getType() : "jar") + ":"