vFrom.setCompareScope(scopedVertices);

        List<MetadataGraphEdge> exList = excidentEdges.computeIfAbsent(vFrom, k -> new ArrayList<>());

        if (!exList.contains(e)) {
            exList.add(e);
        }

        List<MetadataGraphEdge> inList = incidentEdges.computeIfAbsent(vTo, k -> new ArrayList<>());

        if (!inList.contains(e)) {
            inList.add(e);
        }

    val shadowPackagePrefix =
        shadowPackage.takeIf(String::isNotEmpty)
            ?.let { it.replace('.', '/') + "/" }
            ?: ""

    operator fun get(className: String) =
        classes.computeIfAbsent(className) {
            val outputClassName = if (unshadedPackages.matches(className)) className else shadowPackagePrefix + className
            ClassDetails(outputClassName).also { classDetails ->

    }

    private
    fun addExecutedTaskPath(taskPath: String) {
        projectPathToExecutedTaskPaths.computeIfAbsent(taskPathToProjectPath(taskPath)) { mutableListOf() }.add(taskPath)
    }

    private
    fun addFailedTaskPath(taskPath: String) {
        projectPathToFailedTaskPaths.computeIfAbsent(taskPathToProjectPath(taskPath)) { mutableListOf() }.add(taskPath)
    }

    private

                allHandlers.clear();
            }
        }
    }

    @Override
    public ArtifactHandler getArtifactHandler(String id) {
        return allHandlers.computeIfAbsent(id, k -> {
            Type type = typeRegistry.require(id);
            return new DefaultArtifactHandler(
                    id,
                    type.getExtension(),
                    type.getClassifier(),

        }

        private LongAdder getCounter(BuilderProblem.Severity severity) {
            return counters.computeIfAbsent(severity, k -> new LongAdder());
        }

        private List<P> getProblems(BuilderProblem.Severity severity) {
            return problems.computeIfAbsent(severity, k -> new CopyOnWriteArrayList<>());
        }

        lifecycle.allPhases().forEach(phase -> phase.plugins()
                .forEach(plugin -> plugin.getExecutions().forEach(exec -> exec.getGoals()
                        .forEach(goal -> goals.computeIfAbsent(phase.name(), n -> new ArrayList<>())
                                .add(plugin.getGroupId() + ":" + plugin.getArtifactId() + ":" + plugin.getVersion()
                                        + ":" + goal)))));

     * Parses the phase identifier.
     *
     * @param phase the phase identifier.
     * @return the {@link PhaseId}.
     */
    public static synchronized PhaseId of(String phase) {
        return INSTANCES.computeIfAbsent(phase, PhaseId::new);
    }

    /**
     * Constructor.
     *
     * @param phase the phase identifier string.
     */
    private PhaseId(String phase) {
        int phaseStart;

        return Optional.of(require(id));
    }

    @Override
    @Nonnull
    public Type require(String id) {
        requireNonNull(id, "id cannot be null");
        return usedTypes.computeIfAbsent(id, i -> {
            Type type = lookup.lookupList(TypeProvider.class).stream()
                    .flatMap(p -> p.provides().stream())
                    .filter(t -> Objects.equals(id, t.id()))

        // and allow multiple instances per JVM, this may become a pool? derive key based in invokerRequest?
        MavenContext result = residentContext.computeIfAbsent(
                "resident",
                k -> new MavenContext(invokerRequest, false, (MavenOptions)
                        invokerRequest.options().orElse(null)));
        return copyIfDifferent(result, invokerRequest);

        return vertices.get(id);
    }

    public Collection<Vertex> getVertices() {
        return vertices.values();
    }

    Vertex addVertex(String label) {
        return vertices.computeIfAbsent(label, Vertex::new);
    }

    void addEdge(Vertex from, Vertex to) throws CycleDetectedException {
        from.children.add(to);
        to.parents.add(from);
        List<String> cycle = findCycle(to);