final Map<Path, Holder> modelByPath = new ConcurrentHashMap<>();

    final Map<GAKey, Holder> modelByGA = new ConcurrentHashMap<>();

    public static class Holder {
        private volatile boolean set;
        private volatile Model model;

        Holder() {}

        Holder(Model model) {
            this.model = Objects.requireNonNull(model);

                Model model = findRawModel(from, gId, aId);
                if (model != null) {
                    context.modelByGA.put(new GAKey(gId, aId), new Holder(model));
                    context.modelByPath.put(model.getPomFile(), new Holder(model));
                }
                return model;
            }

            @Override
            public Model getRawModel(Path from, Path path) {

        AndArtifactFilter filter2 = new AndArtifactFilter(Arrays.asList(newSubFilter()));

        assertFalse(filter1.equals(null));
        assertTrue(filter1.equals(filter1));
        assertEquals(filter1.hashCode(), filter1.hashCode());

        assertFalse(filter1.equals(filter2));
        assertFalse(filter2.equals(filter1));
    }

    }

    protected DefaultModelRepositoryHolder(DefaultModelRepositoryHolder holder) {
        this.session = holder.session;
        this.repositoryMerging = holder.repositoryMerging;
        this.pomRepositories = List.copyOf(holder.pomRepositories);
        this.externalRepositories = List.copyOf(holder.externalRepositories);
        this.repositories = List.copyOf(holder.repositories);
    }

    @Override

     *
     * @param session The session to use to resolve the model, must not be {@code null}.
     * @param parent The parent coordinates to resolve, must not be {@code null}.
     * @param modified a holder for the updated parent, must not be {@code null}.
     * @return The source of the requested POM, never {@code null}.
     * @throws ModelResolverException If the POM could not be resolved from any configured repository.
     */

        OrArtifactFilter filter2 = new OrArtifactFilter(Arrays.asList(newSubFilter()));

        assertFalse(filter1.equals(null));
        assertTrue(filter1.equals(filter1));
        assertEquals(filter1.hashCode(), filter1.hashCode());

        assertFalse(filter1.equals(filter2));
        assertFalse(filter2.equals(filter1));
    }