*
     * @param parent the parent ClassLoader
     * @param spec the filtering spec for the classloader
     * @return The ClassLoader
     */
    ClassLoader createFilteringClassLoader(ClassLoader parent, FilteringClassLoader.Spec spec);

        assert ClassLoader.getSystemResource("META-INF/services/javax.xml.parsers.SAXParserFactory")

        when:
        def cl = new URLClassLoader(classpath.asURLArray, factory.createFilteringClassLoader(getClass().classLoader, new FilteringClassLoader.Spec()))
        def c = cl.loadClass(DefaultClassLoaderFactoryTestHelper.name)

        then:
        c != DefaultClassLoaderFactoryTestHelper

        when:

        sharedSpec.allowClass(ToolingApiVersion)
        sharedSpec.allowClass(TeeOutputStream)
        sharedSpec.allowClass(ClassLoaderFixture)
        def sharedClassLoader = classLoaderFactory.createFilteringClassLoader(Thread.currentThread().getContextClassLoader(), sharedSpec)

        def parentClassLoader = new MultiParentClassLoader(toolingApi.classLoader, sharedClassLoader)

        if (file != null) {
            return classPath.plus(Collections.singletonList(file));
        }
        return classPath;
    }

    @Override
    public ClassLoader createFilteringClassLoader(ClassLoader parent, FilteringClassLoader.Spec spec) {
        // See the comment for {@link #createIsolatedClassLoader} above
        FilteringClassLoader.Spec classLoaderSpec = new FilteringClassLoader.Spec(spec);

        FilteringClassLoader.Spec filterSpec = new FilteringClassLoader.Spec();
        filterSpec.allowPackage("com.sun.tools");
        filterSpec.allowPackage("com.sun.source");
        return classLoaderFactory.createFilteringClassLoader(
            this.getClass().getClassLoader(),
            filterSpec
        );
    }

    public ContextAwareJavaCompiler getSystemJavaCompiler() {

            if (spec.isFiltered()) {
                parentCachedLoader = getAndRetainLoader(spec.unfiltered(), id, factoryFunction);
                classLoader = classLoaderFactory.createFilteringClassLoader(parentCachedLoader.classLoader, spec.filterSpec);
            } else {
                classLoader = factoryFunction.apply(spec);
            }