checkNotNull(function);
    return Optional.absent();
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    return object == this;
  }

  @Override
  public int hashCode() {
    return 0x79a31aac;
  }

  @Override
  public String toString() {
    return "Optional.absent()";
  }

  private Object readResolve() {
    return INSTANCE;
  }

  public FakeTicker advance(long time, TimeUnit timeUnit) {
    return advance(timeUnit.toNanos(time));
  }

  /** Advances the ticker value by {@code nanoseconds}. */
  @SuppressWarnings("GoodTime") // should accept a java.time.Duration
  @CanIgnoreReturnValue
  public FakeTicker advance(long nanoseconds) {
    nanos.addAndGet(nanoseconds);
    return this;
  }

  /**
   * Advances the ticker value by {@code duration}.

	}
	err = en.WriteInt64(z.Size)
	if err != nil {
		err = msgp.WrapError(err, "Size")
		return
	}
	// write "os"
	err = en.Append(0xa2, 0x6f, 0x73)
	if err != nil {
		return
	}
	err = en.WriteUint64(z.Objects)
	if err != nil {
		err = msgp.WrapError(err, "Objects")
		return
	}
	// write "vs"
	err = en.Append(0xa2, 0x76, 0x73)
	if err != nil {
		return
	}

    if (collection instanceof SortedSet) {
      return sortedSet((SortedSet<E>) collection, mutex);
    }
    if (collection instanceof Set) {
      return set((Set<E>) collection, mutex);
    }
    if (collection instanceof List) {
      return list((List<E>) collection, mutex);
    }
    return collection(collection, mutex);
  }

    /**
     * Returns a simple designator of the options source, such as "cli", "maven.conf", etc.
     *
     * @return a string representing the source of the options
     */
    @Nonnull
    String source();

    /**
     * Returns the user-defined properties for the Maven execution.
     *
     * @return an {@link Optional} containing the map of user properties, or empty if not set
     */
    @Nonnull

    if (left == right) {
      return 0;
    }

    return ((Comparable<Object>) right).compareTo(left);
  }

  @Override
  public <S extends Comparable<?>> Ordering<S> reverse() {
    return Ordering.natural();
  }

  // Override the min/max methods to "hoist" delegation outside loops

  @Override
  public <E extends Comparable<?>> E min(E a, E b) {
    return NaturalOrdering.INSTANCE.max(a, b);
  }

  protected Map<String, Integer> makeEmptyMap() {
    return ImmutableMap.of();
  }

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    return ImmutableMap.of("one", 1, "two", 2, "three", 3);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }

    public int getPageSize() {
        if (size != null) {
            return size;
        }
        return ComponentUtil.getFessConfig().getPagingPageSizeAsInteger();
    }

    public int getCurrentPageNumber() {
        if (page != null) {
            return page;
        }
        return Constants.DEFAULT_ADMIN_PAGE_NUMBER;
    }

  protected Map<String, Integer> makeEmptyMap() {
    return ImmutableMap.of();
  }

  @Override
  protected Map<String, Integer> makePopulatedMap() {
    return ImmutableMap.of("one", 1, "two", 2, "three", 3);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }

    return ImmutableSortedMap.of();
  }

  @Override
  protected SortedMap<String, Integer> makePopulatedMap() {
    return ImmutableSortedMap.of("one", 1, "two", 2, "three", 3);
  }

  @Override
  protected String getKeyNotInPopulatedMap() {
    return "minus one";
  }

  @Override
  protected Integer getValueNotInPopulatedMap() {
    return -1;
  }