T upperEndpoint = range.hasUpperBound() ? range.upperEndpoint() : null;
    BoundType upperBoundType = range.hasUpperBound() ? range.upperBoundType() : OPEN;
    return new GeneralRange<>(
        Ordering.natural(),
        range.hasLowerBound(),
        lowerEndpoint,
        lowerBoundType,
        range.hasUpperBound(),
        upperEndpoint,
        upperBoundType);
  }

    assertTrue(range.hasLowerBound());
    assertEquals(4, (int) range.lowerEndpoint());
    assertEquals(OPEN, range.lowerBoundType());
    assertTrue(range.hasUpperBound());
    assertEquals(8, (int) range.upperEndpoint());
    assertEquals(OPEN, range.upperBoundType());
    assertFalse(range.isEmpty());
    assertEquals("(4..8)", range.toString());
    reserializeAndAssert(range);
  }

  public void testOpen_invalid() {

    assertTrue(range.hasLowerBound());
    assertEquals(4, (int) range.lowerEndpoint());
    assertEquals(OPEN, range.lowerBoundType());
    assertTrue(range.hasUpperBound());
    assertEquals(8, (int) range.upperEndpoint());
    assertEquals(OPEN, range.upperBoundType());
    assertFalse(range.isEmpty());
    assertEquals("(4..8)", range.toString());
    reserializeAndAssert(range);
  }

  public void testOpen_invalid() {

    T upperEndpoint = range.hasUpperBound() ? range.upperEndpoint() : null;
    BoundType upperBoundType = range.hasUpperBound() ? range.upperBoundType() : OPEN;
    return new GeneralRange<>(
        Ordering.natural(),
        range.hasLowerBound(),
        lowerEndpoint,
        lowerBoundType,
        range.hasUpperBound(),
        upperEndpoint,
        upperBoundType);
  }

      return other;
    } else {
      C lowerEndpoint = Ordering.<C>natural().max(this.first(), other.first());
      C upperEndpoint = Ordering.<C>natural().min(this.last(), other.last());
      return (lowerEndpoint.compareTo(upperEndpoint) <= 0)
          ? ContiguousSet.create(Range.closed(lowerEndpoint, upperEndpoint), domain)
          : new EmptyContiguousSet<C>(domain);
    }
  }

  @Override
  public Range<C> range() {

      Collection<Range<C>> candidates;
      if (upperBoundWindow.hasUpperBound()) {
        candidates =
            rangesByLowerBound
                .headMap(upperBoundWindow.upperEndpoint(), false)
                .descendingMap()
                .values();
      } else {
        candidates = rangesByLowerBound.descendingMap().values();
      }

          set.comparator().compare(range.lowerEndpoint(), range.upperEndpoint()) <= 0,
          "set is using a custom comparator which is inconsistent with the natural ordering.");
    }
    if (range.hasLowerBound() && range.hasUpperBound()) {
      return set.subSet(
          range.lowerEndpoint(),
          range.lowerBoundType() == BoundType.CLOSED,
          range.upperEndpoint(),
          range.upperBoundType() == BoundType.CLOSED);

  /**
   * Returns the upper endpoint of this range.
   *
   * @throws IllegalStateException if this range is unbounded above (that is, {@link
   *     #hasUpperBound()} returns {@code false})
   */
  public C upperEndpoint() {
    return upperBound.endpoint();
  }

  /**
   * Returns the type of this range's upper bound: {@link BoundType#CLOSED} if the range includes
   * its upper endpoint, {@link BoundType#OPEN} if it does not.

          map.comparator().compare(range.lowerEndpoint(), range.upperEndpoint()) <= 0,
          "map is using a custom comparator which is inconsistent with the natural ordering.");
    }
    if (range.hasLowerBound() && range.hasUpperBound()) {
      return map.subMap(
          range.lowerEndpoint(),
          range.lowerBoundType() == BoundType.CLOSED,
          range.upperEndpoint(),
          range.upperBoundType() == BoundType.CLOSED);