}
  }

  private WeakReference<ClassLoader> useFrqInSeparateLoader() throws Exception {
    final ClassLoader myLoader = getClass().getClassLoader();
    URLClassLoader sepLoader = new URLClassLoader(getClassPathUrls(), myLoader.getParent());
    // sepLoader is the loader that we will use to load the parallel FinalizableReferenceQueue (FRQ)
    // and friends, and that we will eventually expect to see garbage-collected. The assumption

  // cleared.
  @J2ktIncompatible
  @GwtIncompatible // weak references
  private WeakReference<?> doTestClassUnloading() throws Exception {
    URLClassLoader shadowLoader = new URLClassLoader(getClassPathUrls(), null);
    @SuppressWarnings("unchecked")
    Class<TestEnum> shadowTestEnum =
        (Class<TestEnum>) Class.forName(TestEnum.class.getName(), false, shadowLoader);
    assertNotSame(shadowTestEnum, TestEnum.class);

    System.setProperty("guava.concurrent.generate_cancellation_cause", "true");
    final String concurrentPackage = SettableFuture.class.getPackage().getName();
    classReloader =
        new URLClassLoader(ClassPathUtil.getClassPathUrls()) {
          @GuardedBy("loadedClasses")
          final Map<String, Class<?>> loadedClasses = new HashMap<>();

          @Override
          public Class<?> loadClass(String name) throws ClassNotFoundException {

    System.setProperty("guava.concurrent.generate_cancellation_cause", "true");
    final String concurrentPackage = SettableFuture.class.getPackage().getName();
    classReloader =
        new URLClassLoader(ClassPathUtil.getClassPathUrls()) {
          @GuardedBy("loadedClasses")
          final Map<String, Class<?>> loadedClasses = new HashMap<>();

          @Override
          public Class<?> loadClass(String name) throws ClassNotFoundException {