if (comparator != null) { // can't use ? : because of javac bug 5080917
      return comparator;
    }
    return (Comparator<E>) Ordering.natural();
  }

  /**
   * Returns a live {@link Map} view whose keys are the contents of {@code set} and whose values are
   * computed on demand using {@code function}. To get an immutable <i>copy</i> instead, use {@link
   * #toMap(Iterable, Function)}.
   *

    map.put(four, five);
    i = map.keySet().iterator();
    i.next();
    i.remove();
    assertNotified(listener, four, five, RemovalCause.EXPLICIT);

    map.put(five, six);
    i = map.values().iterator();
    i.next();
    i.remove();
    assertNotified(listener, five, six, RemovalCause.EXPLICIT);

    assertTrue(listener.isEmpty());
  }

    assertNotified(listener, three, four, RemovalCause.EXPLICIT);

    map.put(four, five);
    i = map.keySet().iterator();
    i.next();
    i.remove();
    assertNotified(listener, four, five, RemovalCause.EXPLICIT);

    map.put(five, six);
    i = map.values().iterator();
    i.next();
    i.remove();
    assertNotified(listener, five, six, RemovalCause.EXPLICIT);

    assertTrue(listener.isEmpty());
  }

		return
	}
	ctx = lkctx.Context()
	defer lock.RUnlock(lkctx)

	getObjectNInfo := objectAPI.GetObjectNInfo

	gopts := opts
	gopts.NoLock = true // We already have a lock, we can live with it.
	objInfo, err := getObjectInfo(ctx, bucket, object, gopts)
	if err != nil {
		// Versioning enabled quite possibly object is deleted might be delete-marker

          ClosingFuture<V3> future3,
          ClosingFuture<V4> future4) {
    return new Combiner4<>(future1, future2, future3, future4);
  }

  /**
   * Starts specifying how to combine five {@link ClosingFuture}s into a single pipeline, assuming
   * they all succeed. If any fail, the resulting pipeline will fail.
   *
   * <p>Calling this method allows you to use lambdas or method references typed with the types of

	    a complex constant, with a mantissa of at least 256 bits
	    and a signed binary exponent of at least 16 bits.</li>

	<li>Give an error if unable to represent an integer constant
	    precisely.</li>

	<li>Give an error if unable to represent a floating-point or
	    complex constant due to overflow.</li>

	<li>Round to the nearest representable constant if unable to