public void testSubMap_boundedRange() {
    ImmutableSortedMap<Integer, Integer> map = ImmutableSortedMap.of(2, 0, 4, 0, 6, 0, 8, 0, 10, 0);
    ImmutableSortedMap<Integer, Integer> empty = ImmutableSortedMap.of();

    assertEquals(map, Maps.subMap(map, Range.closed(0, 12)));
    assertEquals(ImmutableSortedMap.of(2, 0, 4, 0), Maps.subMap(map, Range.closed(0, 4)));

  public void testSubMap_boundedRange() {
    ImmutableSortedMap<Integer, Integer> map = ImmutableSortedMap.of(2, 0, 4, 0, 6, 0, 8, 0, 10, 0);
    ImmutableSortedMap<Integer, Integer> empty = ImmutableSortedMap.of();

    assertEquals(map, Maps.subMap(map, Range.closed(0, 12)));
    assertEquals(ImmutableSortedMap.of(2, 0, 4, 0), Maps.subMap(map, Range.closed(0, 4)));

                return wrap(delegate);
              }
            });
  }

  public void testEquals() {
    NavigableMap<Integer, String> map1 = ImmutableSortedMap.of(1, "one");
    NavigableMap<Integer, String> map2 = ImmutableSortedMap.of(2, "two");
    new EqualsTester()
        .addEqualityGroup(map1, wrap(map1), wrap(map1))
        .addEqualityGroup(map2, wrap(map2))
        .testEquals();
  }

    assertEquals(ImmutableMap.of(), ArbitraryInstances.get(ImmutableMap.class));
    assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(SortedMap.class));
    assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(ImmutableSortedMap.class));
    assertEquals(ImmutableMultiset.of(), ArbitraryInstances.get(Multiset.class));

    assertEquals(ImmutableMap.of(), ArbitraryInstances.get(ImmutableMap.class));
    assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(SortedMap.class));
    assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(ImmutableSortedMap.class));
    assertEquals(ImmutableMultiset.of(), ArbitraryInstances.get(Multiset.class));

  }

  /**
   * Creates a <i>mutable</i>, empty {@code TreeMap} instance using the natural ordering of its
   * elements.
   *
   * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSortedMap#of()} instead.
   *
   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
   * use the {@code TreeMap} constructor directly, taking advantage of <a