*
   * if (guardExpression) {
   *    throw new BadException(badMsg(...));
   * }
   *
   * The alternative natural refactorings into void or Exception-returning methods are much slower.
   * This is a big deal - we're talking factors of 2-8 in microbenchmarks, not just 10-20%. (This is
   * a hotspot optimizer bug, which should be fixed, but that's a separate, big project).
   *

   *
   * if (guardExpression) {
   *    throw new BadException(badMsg(...));
   * }
   *
   * The alternative natural refactorings into void or Exception-returning methods are much slower.
   * This is a big deal - we're talking factors of 2-8 in microbenchmarks, not just 10-20%. (This is
   * a hotspot optimizer bug, which should be fixed, but that's a separate, big project).
   *

        ClosingFuture.submit(
                closer -> {
                  closer.eventuallyClose(closeable1, closingExecutor);
                  closer.eventuallyClose(closeable2, closingExecutor);
                  return closeable3;
                },
                executor)
            .transform(
                (DeferredCloser closer, TestCloseable v) -> {

        ClosingFuture.submit(
                closer -> {
                  closer.eventuallyClose(closeable1, closingExecutor);
                  closer.eventuallyClose(closeable2, closingExecutor);
                  return closeable3;
                },
                executor)
            .transform(
                (DeferredCloser closer, TestCloseable v) -> {

   * is merely copied. Only as the power set is iterated are the individual subsets created, and
   * these subsets themselves occupy only a small constant amount of memory.
   *
   * @param set the set of elements to construct a power set from
   * @return the power set, as an immutable set of immutable sets

   * is merely copied. Only as the power set is iterated are the individual subsets created, and
   * these subsets themselves occupy only a small constant amount of memory.
   *
   * @param set the set of elements to construct a power set from
   * @return the power set, as an immutable set of immutable sets

		nsUnlocker = func() { lock.RUnlock(lkctx) }
		unlockOnDefer = true
	}

	checkPrecondFn := opts.CheckPrecondFn
	opts.CheckPrecondFn = nil // do not need to apply pre-conditions at lower layer.
	opts.NoLock = true        // no locks needed at lower levels for getObjectInfo()
	objInfo, zIdx, err := z.getLatestObjectInfoWithIdx(ctx, bucket, object, opts)
	if err != nil {
		if objInfo.DeleteMarker {
			if opts.VersionID == "" {

	}
	// Prefer newest modtime.
	if x.ModTime != o.ModTime {
		return x.ModTime > o.ModTime
	}

	// The following doesn't make too much sense, but we want sort to be consistent nonetheless.
	// Prefer lower types
	if x.Type != o.Type {
		return x.Type < o.Type
	}
	// Consistent sort on signature
	if v := bytes.Compare(x.Signature[:], o.Signature[:]); v != 0 {
		return v > 0
	}
	// On ID mismatch

    public @Nullable E higher(E e) {
      synchronized (mutex) {
        return delegate().higher(e);
      }
    }

    @Override
    public @Nullable E lower(E e) {
      synchronized (mutex) {
        return delegate().lower(e);
      }
    }

    @Override
    public @Nullable E pollFirst() {
      synchronized (mutex) {
        return delegate().pollFirst();
      }
    }

    public @Nullable E higher(E e) {
      synchronized (mutex) {
        return delegate().higher(e);
      }
    }

    @Override
    public @Nullable E lower(E e) {
      synchronized (mutex) {
        return delegate().lower(e);
      }
    }

    @Override
    public @Nullable E pollFirst() {
      synchronized (mutex) {
        return delegate().pollFirst();
      }
    }