/**
     * Sets whether the build should be resumed from the data in the resume.properties file.
     * @param resume Whether or not to resume a previous build.
     * @return This request, never {@code null}.
     */
    MavenExecutionRequest setResume(boolean resume);

    /**
     * @return Whether the build should be resumed from the data in the resume.properties file.
     */
    boolean isResume();

                                                .build())
                                        .build();
                                throw new IOException("Snapshot information corrupted with remote repository data"
                                        + ", please verify that no remote repository uses the id '"
                                        + repository.getId() + "'");
                            }
                        }

        final CollectStepData data = mock(CollectStepData.class);

        RequestTrace haveItFirst = RequestTrace.newChild(null, data)
                .newChild("foo")
                .newChild("bar")
                .newChild("baz");
        assertThat(ReverseTreeRepositoryListener.lookupCollectStepData(haveItFirst), sameInstance(data));

        RequestTrace haveItLast = RequestTrace.newChild(null, "foo")

 * 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);

/**
 * Caches raw plugin descriptors. A raw plugin descriptor is a descriptor that has just been extracted from the plugin
 * artifact and does not contain any runtime specific data. The cache must not be used for descriptors that hold runtime
 * data like the plugin realm. <strong>Warning:</strong> This is an internal utility interface that is only public for

        }
    }

    @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");

    }

    @SuppressWarnings("unchecked")
    private ConcurrentMap<Key, PluginVersionResult> getCache(PluginVersionRequest request) {
        SessionData data = request.getRepositorySession().getData();
        return (ConcurrentMap<Key, PluginVersionResult>)
                data.computeIfAbsent(CACHE_KEY, () -> new ConcurrentHashMap<>(256));
    }

    private static Key getKey(PluginVersionRequest request) {

    @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,

                    }
                } else {
                    // System.out.println("+++>"+v.getMd().toDomainString()+" still has "+edge.toString() );
                    // fill in domain md with actual version data
                    ArtifactMetadata md = v.getMd();
                    ArtifactMetadata newMd = new ArtifactMetadata(
                            md.getGroupId(),
                            md.getArtifactId(),