Assert.fail()
        } catch (ClassNotFoundException) {
            // expected
        }
    }

    ClassLoader filter(Class<?> aClass) {
        def spec = new FilteringClassLoader.Spec()
        spec.allowClass(aClass)
        return new FilteringClassLoader(aClass.classLoader, spec)
    }

    ClassLoader isolated(ClassLoader parent = ClassLoader.systemClassLoader.parent, Class<?>... classes) {

    @Override
    protected ObjectStreamClass readClassDescriptor() throws IOException, ClassNotFoundException {
        Class<?> aClass = readClass();
        ObjectStreamClass descriptor = ObjectStreamClass.lookupAny(aClass);
        if (descriptor == null) {
            throw new ClassNotFoundException(aClass.getName());
        }
        return descriptor;
    }

    @Override

            SecurityManager securityManager;
            try {
                Class<?> aClass = systemClassLoader.loadClass(securityManagerType);
                securityManager = (SecurityManager) JavaReflectionUtil.newInstance(aClass);
            } catch (Exception e) {