return Optional.empty();
    }

    @Nonnull
    @Override
    public Collection<Artifact> getAttachedArtifacts(Project project) {
        InternalMavenSession session = ((DefaultProject) project).getSession();
        Collection<Artifact> attached = map(
                getMavenProject(project).getAttachedArtifacts(),
                a -> session.getArtifact(RepositoryUtils.toArtifact(a)));

        try {
            mavenProjectHelper.attachArtifact(mavenProject, "java-source", artifactFile);
            assertEquals(1, mavenProject.getAttachedArtifacts().size());
            mavenProjectHelper.attachArtifact(mavenProject, "java-source", artifactFile);
            assertEquals(1, mavenProject.getAttachedArtifacts().size());
        } finally {
            Files.deleteIfExists(artifactFile.toPath());
        }
    }

     */
    @Nonnull
    Optional<Path> getPath(Project project);

    /**
     * Returns an immutable collection of attached artifacts for given project.
     */
    @Nonnull
    Collection<Artifact> getAttachedArtifacts(Project project);

    /**
     * Returns project's all artifacts as immutable collection. The list contains all artifacts, even the attached ones,

     */
    private Stream<org.apache.maven.artifact.Artifact> getProjectArtifacts(MavenProject project) {
        return Stream.concat(Stream.of(project.getArtifact()), project.getAttachedArtifacts().stream());
    }

    private String id(org.apache.maven.artifact.Artifact artifact) {
        return artifact.getGroupId()
                + ":" + artifact.getArtifactId()

        new DefaultConsumerPomArtifactTransformer((session, project, src) -> null)
                .injectTransformedArtifacts(systemSessionMock, emptyProject);

        assertThat(emptyProject.getAttachedArtifacts()).isEmpty();
    }

    private static class NoTransformerContext implements TransformerContext {
        @Override
        public String getUserProperty(String key) {
            return null;
        }

            setActiveProfiles((Collections.unmodifiableList(project.getActiveProfiles())));
        }

        if (project.getAttachedArtifacts() != null) {
            // clone properties modifiable by plugins in a forked lifecycle
            setAttachedArtifacts(new ArrayList<>(project.getAttachedArtifacts()));
        }

        if (project.getCompileSourceRoots() != null) {
            // clone source roots

                        "pom".equals(project.getPackaging()) ? Stream.empty() : Stream.of(project.getArtifact())),
                // attached artifacts
                project.getAttachedArtifacts().stream());
        return artifacts.map(RepositoryUtils::toArtifact);
    }

    private boolean isRegularFile(Artifact artifact) {
        return artifact.getFile() != null && artifact.getFile().isFile();