void putLongLittleEndian(byte[] array, int offset, long value);

    boolean usesFastPath();
  }

  /** VarHandle-based implementation. */
  @J2ObjCIncompatible
  // We use this class only after confirming that VarHandle is available at runtime.
  @SuppressWarnings("Java8ApiChecker")
  @IgnoreJRERequirement
  private enum VarHandleLittleEndianBytes implements LittleEndianBytes {

  }

  /** {@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}.
   */