}

    /**
     * CacheRecord
     */
    class CacheRecord {

        private final Set<Artifact> artifacts;

        private final LifecycleExecutionException exception;

        CacheRecord(Set<Artifact> artifacts) {
            this.artifacts = artifacts;
            this.exception = null;
        }

        CacheRecord(LifecycleExecutionException exception) {

    }

    @Override
    public CacheRecord get(Key key) throws LifecycleExecutionException {
        CacheRecord cacheRecord = cache.get(key);
        if (cacheRecord != null && cacheRecord.getException() != null) {
            throw cacheRecord.getException();
        }
        return cacheRecord;
    }

    @Override
    public CacheRecord put(Key key, Set<Artifact> projectArtifacts) {

            DependencyFilter extensionFilter,
            List<RemoteRepository> repositories,
            RepositorySystemSession session);

    CacheRecord get(Key key) throws PluginResolutionException;

    CacheRecord put(Key key, List<Artifact> pluginArtifacts);

    CacheRecord put(Key key, PluginResolutionException e);

    void flush();

    /**

        CacheRecord cacheRecord = cache.get(key);

        if (cacheRecord != null && cacheRecord.getException() != null) {
            throw cacheRecord.getException();
        }

        return cacheRecord;
    }

    public CacheRecord put(Key key, List<Artifact> pluginArtifacts) {
        Objects.requireNonNull(pluginArtifacts, "pluginArtifacts cannot be null");

        assertUniqueKey(key);

        CacheRecord(ClassRealm realm, DependencyFilter extensionArtifactFilter) {
            this.realm = realm;
            this.extensionArtifactFilter = extensionArtifactFilter;
        }
    }

    Key createKey(List<? extends ClassRealm> extensionRealms);

    CacheRecord get(Key key);

     */
    interface Key {
        // marker interface for cache keys
    }

    /**
     * CacheRecord
     */
    class CacheRecord {

        private final ClassRealm realm;

        private final ExtensionDescriptor descriptor;

        private final List<Artifact> artifacts;

        CacheRecord(ClassRealm realm, ExtensionDescriptor descriptor, List<Artifact> artifacts) {
            this.realm = realm;

public interface PluginRealmCache {
    /**
     * CacheRecord
     */
    class CacheRecord {
        public ClassRealm getRealm() {
            return realm;
        }

        public List<Artifact> getArtifacts() {
            return artifacts;
        }

        private final ClassRealm realm;

        private final List<Artifact> artifacts;

        public CacheRecord(ClassRealm realm, List<Artifact> artifacts) {

        } else {
            return new ArrayList<>();
        }
    }

    public ProjectRealmCache.CacheRecord createProjectRealm(
            MavenProject project, Model model, ProjectBuildingRequest request) {
        return new ProjectRealmCache.CacheRecord(null, null);
    }

    public void selectProjectRealm(MavenProject project) {}

                            e);
        }
        project.setPluginArtifactRepositories(pluginRepositories);

        if (event.request().isProcessPlugins()) {
            try {
                ProjectRealmCache.CacheRecord record =
                        projectBuildingHelper.createProjectRealm(project, model, projectBuildingRequest);

                project.setClassRealm(record.getRealm());

     * @return The record with the project realm and extension artifact filter, never {@code null}.
     * @throws PluginResolutionException If any build extension could not be resolved.
     */
    ProjectRealmCache.CacheRecord createProjectRealm(MavenProject project, Model model, ProjectBuildingRequest request)
            throws PluginResolutionException, PluginVersionResolutionException, PluginManagerException;

    /**