setImplementation(Deque.class, ArrayDeque.class);
    setImplementation(OutputStream.class, ByteArrayOutputStream.class);
    setImplementation(PrintStream.class, Dummies.InMemoryPrintStream.class);
    setImplementation(PrintWriter.class, Dummies.InMemoryPrintWriter.class);
    setImplementation(Queue.class, ArrayDeque.class);
    setImplementation(Random.class, Dummies.DeterministicRandom.class);
    setImplementation(

    setImplementation(Deque.class, ArrayDeque.class);
    setImplementation(OutputStream.class, ByteArrayOutputStream.class);
    setImplementation(PrintStream.class, Dummies.InMemoryPrintStream.class);
    setImplementation(PrintWriter.class, Dummies.InMemoryPrintWriter.class);
    setImplementation(Queue.class, ArrayDeque.class);
    setImplementation(Random.class, Dummies.DeterministicRandom.class);
    setImplementation(

        MojoDescriptor mojo = new MojoDescriptor();
        mojo.setPluginDescriptor(pluginDescriptor);

        mojo.setGoal(c.getChild("goal").getValue());

        mojo.setImplementation(c.getChild("implementation").getValue());

        PlexusConfiguration langConfig = c.getChild("language");

        if (langConfig != null) {
            mojo.setLanguage(langConfig.getValue());
        }

            this.registration = registration;
        }

        @Override
        public TypeRegistrationBuilder<S> withImplementation(ModelType<?> implementationType) {
            registration.setImplementation(implementationType, source);
            return this;
        }

        @Override
        public TypeRegistrationBuilder<S> withInternalView(ModelType<?> internalView) {

        this.setOnlineRequired(md.isOnlineRequired());
        this.setProjectRequired(md.isProjectRequired());
        this.setSince(md.getSince());
        this.setThreadSafe(true);
        this.setImplementation(md.getImplementation());
        try {
            this.setParameters(md.getParameters().stream().map(Parameter::new).collect(Collectors.toList()));
        } catch (DuplicateParameterException e) {

            implementation("org:foo:1.0") // is getImplementation().add("org:foo:1.0")

            // Add a dependency with explicit coordinate parameters
            implementation(module(group = "org", name = "foo", version = "1.0")) // is getImplementation().add(module("org", "foo", "1.0"))

            // Add dependencies on projects
            implementation(project(":path")) // is getImplementation().add(project(":path"))

    @Inject
    public DefaultToolchainSpec() {
        getVendor().convention(getConventionVendor());
        getImplementation().convention(getConventionImplementation());
    }
    @Override
    public JavaToolchainSpecInternal.Key toKey() {
        return new Key(getLanguageVersion().getOrNull(), getVendor().getOrNull(), getImplementation().getOrNull());
    }

    @Override
    public boolean isConfigured() {

        this.implementation = spec.getImplementation().get().toString();
    }

    @Optional
    @Input
    JavaLanguageVersion getLanguageVersion() {
        return javaLanguageVersion;
    }

    @Input
    String getVendor() {
        return vendor;
    }

    @Input
    String getImplementation() {
        return implementation;
    }

        final Hasher cacheKeyHasher = Hashing.newHasher();

        logger.warn("Appending implementation to build cache key: {}",
            beforeExecutionState.getImplementation());
        beforeExecutionState.getImplementation().appendToHasher(cacheKeyHasher);

        beforeExecutionState.getAdditionalImplementations().forEach(additionalImplementation -> {

// end::custom-dependencies-type[]

// tag::custom-dependencies-scopes[]
    /**
     * Dependency scope called "implementation"
     */
    DependencyCollector getImplementation();
// end::custom-dependencies-scopes[]