/**
   * This classloader disallows {@link java.lang.invoke.VarHandle}, which will prevent us from
   * selecting the {@code VarHandleAtomicHelper} strategy.
   */
  private static final ClassLoader NO_VAR_HANDLE =
      getClassLoader(ImmutableSet.of("java.lang.invoke.VarHandle"));

  /**
   * This classloader disallows {@link java.lang.invoke.VarHandle} and {@link sun.misc.Unsafe},

  }

  /** {@link AtomicHelper} based on {@link VarHandle}. */
  @J2ObjCIncompatible
  // We use this class only after confirming that VarHandle is available at runtime.
  @SuppressWarnings("Java8ApiChecker")
  @IgnoreJRERequirement
  private static final class VarHandleAtomicHelper extends AtomicHelper {
    static final VarHandle waiterThreadUpdater;
    static final VarHandle waiterNextUpdater;

  /**
   * Performs a {@linkplain java.lang.invoke.VarHandle#compareAndSet compare-and-set} operation on
   * {@link #listenersField}.
   */
  final boolean casListeners(@Nullable Listener expect, Listener update) {
    return ATOMIC_HELPER.casListeners(this, expect, update);
  }

  /**
   * Performs a {@linkplain java.lang.invoke.VarHandle#getAndSet get-and-set} operation on {@link
   * #listenersField}.
   */

            new byte[] {(byte) 1, LEAST},
            new byte[] {GREATEST, GREATEST - (byte) 1},
            new byte[] {GREATEST, GREATEST},
            new byte[] {GREATEST, GREATEST, GREATEST});

    // The VarHandle, Unsafe, or Java implementation.
    Comparator<byte[]> comparator = UnsignedBytes.lexicographicalComparator();
    Helpers.testComparator(comparator, ordered);