return session;
    }

    private static final char[] hexCode = "0123456789ABCDEF".toCharArray();

    private static String printHexBinary(byte[] data) {
        StringBuilder r = new StringBuilder(data.length * 2);
        for (byte b : data) {
            r.append(hexCode[(b >> 4) & 0xF]);
            r.append(hexCode[(b & 0xF)]);
        }
        return r.toString();
    }

        return (T) computeIfAbsent(new GavCacheKey(groupId, artifactId, version, tag), data);
    }

    @Override
    @SuppressWarnings({"unchecked"})
    public <T> T computeIfAbsent(Source path, String tag, Supplier<T> data) {
        return (T) computeIfAbsent(new SourceCacheKey(path, tag), data);
    }

    @Inject
    private ArtifactRepositoryFactory artifactRepositoryFactory;

    @Test
    void testUnnecessaryRepositoryLookup() throws Exception {
        Artifact artifact = createTestPomArtifact("target/test-data/get-missing-pom");

        List<ArtifactRepository> repos = new ArrayList<>();
        repos.add(artifactRepositoryFactory.createArtifactRepository(

    }

    @Nonnull
    @Override
    public SessionData getData() {
        org.eclipse.aether.SessionData data = session.getData();
        return new SessionData() {
            @Override
            public <T> void set(@Nonnull Key<T> key, @Nullable T value) {
                data.set(key, value);
            }

            @Override

 * identity of a model. The tag allows for further classification of the associated data on the sole discretion of the
 * model builder.
 *
 */
public interface ModelCache {

    <T> T computeIfAbsent(String groupId, String artifactId, String version, String tag, Supplier<T> data);

    <T> T computeIfAbsent(Source path, String tag, Supplier<T> data);

        }
    }

    @Override
    public Optional<String> getString(URI relativeSource, Charset charset) {
        requireNonNull(charset, "charset is null");
        Optional<byte[]> data = getBytes(relativeSource);
        return data.map(bytes -> new String(bytes, charset));
    }

    @Override
    public void put(Path source, URI relativeTarget) {
        requireNonNull(source, "source is null");

    @Nonnull
    public Type require(String id) {
        nonNull(id, "id");
        return usedTypes.computeIfAbsent(id, i -> {
            Type type = types.get(id);
            if (type == null) {
                // Copy data as the ArtifactHandler is not immutable, but Type should be.
                ArtifactHandler handler = manager.getArtifactHandler(id);
                type = new DefaultType(
                        id,