for (Element key : elems.getValuesInSet()) {
      contents.put(key, key);
    }
    map = mapsImpl.create(contents);
  }

  @Benchmark
  @Footprint(exclude = Element.class)
  public Map<Element, Element> create() throws Exception {
    return mapsImpl.create(contents);
  }

  @Benchmark
  public int iterate() {
    long retVal = 0;
    for (Object entry : map.entrySet()) {
      retVal += entry.hashCode();
    }

   *   <li>uniqueness: unless {@code a.isEmpty()}, {@code ContiguousSet.create(a,
   *       domain).equals(ContiguousSet.create(b, domain))} implies {@code
   *       a.canonical(domain).equals(b.canonical(domain))}
   *   <li>idempotence: {@code a.canonical(domain).canonical(domain).equals(a.canonical(domain))}
   * </ul>
   *
   * <p>Furthermore, this method guarantees that the range returned will be one of the following

    create().isEmpty();
    create().iterator();
    create().remove("foo");
    create().removeAll(ImmutableList.of("foo"));
    create().retainAll(ImmutableList.of("foo"));
    create().size();
    create().toArray();
    create().toArray(new String[] {"foo"});
    create().addFirst("e");
    create().addLast("e");
    create().offerFirst("e");
    create().offerLast("e");
    create().removeFirst();

            ContiguousSet.create(Range.closed(1, 3), integers()),
            ContiguousSet.closed(1, 3),
            ContiguousSet.create(Range.closedOpen(1, 4), integers()),
            ContiguousSet.closedOpen(1, 4),
            ContiguousSet.create(Range.openClosed(0, 3), integers()),
            ContiguousSet.create(Range.open(0, 4), integers()),
            ContiguousSet.create(Range.closed(1, 3), NOT_EQUAL_TO_INTEGERS),

            ContiguousSet.create(Range.closed(1, 3), integers()),
            ContiguousSet.closed(1, 3),
            ContiguousSet.create(Range.closedOpen(1, 4), integers()),
            ContiguousSet.closedOpen(1, 4),
            ContiguousSet.create(Range.openClosed(0, 3), integers()),
            ContiguousSet.create(Range.open(0, 4), integers()),
            ContiguousSet.create(Range.closed(1, 3), NOT_EQUAL_TO_INTEGERS),

    ArrayTable<String, Integer, Character> table =
        create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertEquals((Character) 'b', table.erase("bar", 1));
    assertNull(table.get("bar", 1));
    assertEquals(9, table.size());
    assertNull(table.erase("bar", 1));
    assertNull(table.erase("foo", 2));
    assertNull(table.erase("dog", 1));
    assertNull(table.erase("bar", 5));
    assertNull(table.erase(null, 1));

    ArrayTable<String, Integer, Character> table =
        create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    assertEquals((Character) 'b', table.erase("bar", 1));
    assertNull(table.get("bar", 1));
    assertEquals(9, table.size());
    assertNull(table.erase("bar", 1));
    assertNull(table.erase("foo", 2));
    assertNull(table.erase("dog", 1));
    assertNull(table.erase("bar", 5));
    assertNull(table.erase(null, 1));

    return new TestEnumMultisetGenerator() {
      @Override
      protected Multiset<AnEnum> create(AnEnum[] elements) {
        return (elements.length == 0)
            ? EnumMultiset.create(AnEnum.class)
            : EnumMultiset.create(asList(elements));
      }
    };
  }

  private enum Color {
    BLUE,
    RED,
    YELLOW,
    GREEN,
    WHITE
  }

      @Override
      Map<Element, Element> create(Collection<Element> keys) {
        return Collections.unmodifiableMap(Hash.create(keys));
      }
    },
    SyncHM {
      @Override
      Map<Element, Element> create(Collection<Element> keys) {
        return Collections.synchronizedMap(Hash.create(keys));
      }
    },
    Tree {
      @Override
      Map<Element, Element> create(Collection<Element> keys) {

    Multiset<String> c = HashMultiset.create();
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertTrue(multiset.isEmpty());
  }

  public void testCopyOf_multiset_oneElement() {
    Multiset<String> c = HashMultiset.create(asList("a"));
    Multiset<String> multiset = ImmutableMultiset.copyOf(c);
    assertEquals(HashMultiset.create(asList("a")), multiset);
  }