*
     * @return the class realm of core.
     */
    @Nonnull
    ClassRealm getRealm();

    /**
     * Shorthand method to obtain the {@link ClassWorld} used for Maven Core.
     *
     * @return the class world in use.
     */
    @Nonnull
    default ClassWorld getClassWorld() {
        return getRealm().getWorld();
    }

    private final CoreExports exports;

    @Inject
    public CoreExportsProvider(CoreRealm coreRealm) {
        this(new CoreExports(CoreExtensionEntry.discoverFrom(coreRealm.getRealm())));
    }

    public CoreExportsProvider(CoreExports exports) {
        this.exports = Objects.requireNonNull(exports);
    }

    public CoreExports get() {
        return exports;
    }

    private final PlexusContainer container;

    @Inject
    public DefaultCoreRealm(PlexusContainer container) {
        this.container = container;
    }

    @Override
    public ClassRealm getRealm() {
        return container.getContainerRealm();
    }

    /**
     * A cache key.
     */
    interface Key {
        // marker interface for cache keys
    }

    /**
     * CacheRecord
     */
    class CacheRecord {

        public ClassRealm getRealm() {
            return realm;
        }

        public DependencyFilter getExtensionArtifactFilter() {
            return extensionArtifactFilter;
        }

        private final ClassRealm realm;

            this.realm = realm;
            this.descriptor = descriptor;
            this.artifacts = artifacts;
        }

        public ClassRealm getRealm() {
            return realm;
        }

        public ExtensionDescriptor getDescriptor() {
            return descriptor;
        }

        public List<Artifact> getArtifacts() {

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

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

        private final ClassRealm realm;

            });

            pluginDescriptor.setClassRealm(cacheRecord.getRealm());
            pluginDescriptor.setArtifacts(new ArrayList<>(cacheRecord.getArtifacts()));
            for (ComponentDescriptor<?> componentDescriptor : pluginDescriptor.getComponents()) {
                componentDescriptor.setRealm(cacheRecord.getRealm());
            }

            pluginRealmCache.register(project, cacheKey, cacheRecord);

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

                project.setClassRealm(record.getRealm());
                project.setExtensionDependencyFilter(record.getExtensionArtifactFilter());
            } catch (PluginResolutionException | PluginManagerException | PluginVersionResolutionException e) {

                }
            }

            @Override
            public ClassLoader getClassLoader() {
                return delegate.getMojoDescriptor().getRealm();
            }

            @Override
            public Artifact getArtifact() {
                org.apache.maven.artifact.Artifact artifact =

            ExtensionRealmCache.CacheRecord recordRealm =
                    pluginManager.setupExtensionsRealm(project, plugin, request.getRepositorySession());

            final ClassRealm extensionRealm = recordRealm.getRealm();
            final ExtensionDescriptor extensionDescriptor = recordRealm.getDescriptor();
            final List<Artifact> artifacts = recordRealm.getArtifacts();

            extensionRealms.add(extensionRealm);