*/
  public static <E> Set<Set<E>> combinations(Set<E> set, int size) {
    ImmutableMap<E, Integer> index = Maps.indexMap(set);
    checkNonnegative(size, "size");
    checkArgument(size <= index.size(), "size (%s) must be <= set.size() (%s)", size, index.size());
    if (size == 0) {
      return ImmutableSet.of(ImmutableSet.of());
    } else if (size == index.size()) {
      return ImmutableSet.of(index.keySet());
    }

    @Required
    @Size(max = 200)
    public String name;

    /** The description of the file configuration (maximum 1000 characters). */
    @Size(max = 1000)
    public String description;

    /** The file paths to crawl (required, must be valid file URIs). */
    @Required
    @UriType(protocolType = ProtocolType.FILE)
    @CustomSize(maxKey = "form.admin.max.input.size")
    public String paths;

    // targets.size() < size() / log(size())
    // TODO(kevinb): see if we can share code with OrderedIterator after it
    // graduates from labs.
    if (targets instanceof Multiset) {
      targets = ((Multiset<?>) targets).elementSet();
    }
    if (!SortedIterables.hasSameComparator(comparator(), targets) || (targets.size() <= 1)) {
      return super.containsAll(targets);
    }

        assertEquals(1, result.get(ConfigName.CONFIG).size());
        assertEquals(1, result.get(ConfigName.CLIENT).size());
        assertEquals(1, result.get(ConfigName.XPATH).size());
        assertEquals(1, result.get(ConfigName.META).size());
        assertEquals(1, result.get(ConfigName.VALUE).size());
        assertEquals(1, result.get(ConfigName.SCRIPT).size());
        assertEquals(1, result.get(ConfigName.FIELD).size());

    this.values = array;
    this.rowKeyToIndex = Maps.indexMap(rowSpace);
    this.columnKeyToIndex = Maps.indexMap(columnSpace);
    rowCounts = new int[rowKeyToIndex.size()];
    columnCounts = new int[columnKeyToIndex.size()];
    int[] cellRowIndices = new int[cellList.size()];
    int[] cellColumnIndices = new int[cellList.size()];

  private final transient int size;

  @LazyInit private transient @Nullable ImmutableSet<E> elementSet;

  RegularImmutableMultiset(ObjectCountHashMap<E> contents) {
    this.contents = contents;
    long size = 0;
    for (int i = 0; i < contents.size(); i++) {
      size += contents.getValue(i);
    }
    this.size = Ints.saturatedCast(size);
  }

  @Override
  boolean isPartialView() {

    }

    /**
     * Gets the total content size of all documents in this list.
     *
     * @return the total content size in bytes
     */
    public long getContentSize() {
        return contentSize;
    }

    /**
     * Adds to the total content size of this document list.
     *
     * @param contentSize the content size to add in bytes
     */

    }
    assertEquals(ITERATIONS, map.size());

    map.clear();
    assertEquals(0, map.size());
    assertTrue(map.isEmpty());
  }

  public void testSum() {
    AtomicLongMap<Object> map = AtomicLongMap.create();
    long sum = 0;
    for (int i = 0; i < ITERATIONS; i++) {
      map.put(new Object(), i);
      sum += i;
    }
    assertEquals(ITERATIONS, map.size());
    assertEquals(sum, map.sum());

    /** Configuration name for identifying this data source */
    @Required
    @Size(max = 200)
    public String name;

    /** Optional description of this data configuration */
    @Size(max = 1000)
    public String description;

    /** Handler class name for processing this data source */
    @Required
    @CustomSize(maxKey = "form.admin.max.input.size")
    public String handlerName;

    assertEquals(size + 2, multimap().size());
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  public void testPutNullValue_supported() {
    int size = getNumElements();

    multimap().put(k3(), null);

    assertGet(k3(), Lists.newArrayList((V) null)); // ImmutableList.of can't take null.
    assertEquals(size + 1, multimap().size());
  }