} else {
      return RegularImmutableMultiset.create(entries);
    }
  }

  ImmutableMultiset() {}

  @Override
  public UnmodifiableIterator<E> iterator() {
    final Iterator<Entry<E>> entryIterator = entrySet().iterator();
    return new UnmodifiableIterator<E>() {
      int remaining;
      @CheckForNull E element;

      @Override
      public boolean hasNext() {

 * need for a distinct {@code ImmutableBiMultimap} type.
 *
 * <p><a id="iteration"></a>
 *
 * <p><b>Key-grouped iteration.</b> All view collections follow the same iteration order. In all
 * current implementations, the iteration order always keeps multiple entries with the same key
 * together. Any creation method that would customarily respect insertion order (such as {@link

 * need for a distinct {@code ImmutableBiMultimap} type.
 *
 * <p><a id="iteration"></a>
 *
 * <p><b>Key-grouped iteration.</b> All view collections follow the same iteration order. In all
 * current implementations, the iteration order always keeps multiple entries with the same key
 * together. Any creation method that would customarily respect insertion order (such as {@link

  }

  /**
   * Returns an immutable copy of the provided table.
   *
   * <p>The {@link Table#cellSet()} iteration order of the provided table determines the iteration
   * ordering of all views in the returned table. Note that some views of the original table and the
   * copied table may have different iteration orders. For more control over the ordering, create a

    }
    return builder.build();
  }

  ImmutableMultiset() {}

  @Override
  public UnmodifiableIterator<E> iterator() {
    final Iterator<Entry<E>> entryIterator = entrySet().iterator();
    return new UnmodifiableIterator<E>() {
      int remaining;
      @CheckForNull E element;

      @Override
      public boolean hasNext() {

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@code Multiset} implementation with predictable iteration order. Its iterator orders elements
 * according to when the first occurrence of the element was added. When the multiset contains
 * multiple instances of an element, those instances are consecutive in the iteration order. If all
 * occurrences of an element are removed, after which that element is added to the multiset, the

     * than once. The iteration order of the returned map is the order in which entries were
     * inserted into the builder, unless {@link #orderEntriesByValue} was called, in which case
     * entries are sorted by value. If a key was added more than once, it appears in iteration order
     * based on the first time it was added, again unless {@link #orderEntriesByValue} was called.

        start = System.currentTimeMillis();
        for (Iterator<Map.Entry<String, Object>> i = hmap.entrySet().iterator(); i.hasNext();) {
            i.next();
        }
        System.out.println("HashMap iteration:" + (System.currentTimeMillis() - start));

        start = System.currentTimeMillis();
        for (Iterator<Map.Entry<String, Object>> i = amap.entrySet().iterator(); i.hasNext();) {
            i.next();
        }

    // having inconsistent iteration orderings.
    Map<Currency, Country> map =
        ImmutableMap.of(
            Currency.DOLLAR, Country.CANADA,
            Currency.PESO, Country.CHILE,
            Currency.FRANC, Country.SWITZERLAND);
    EnumBiMap<Currency, Country> bimap = EnumBiMap.create(map);

    Iterator<Currency> iter = bimap.keySet().iterator();
    assertEquals(Currency.DOLLAR, iter.next());

    // having inconsistent iteration orderings.
    Map<Currency, Country> map =
        ImmutableMap.of(
            Currency.DOLLAR, Country.CANADA,
            Currency.PESO, Country.CHILE,
            Currency.FRANC, Country.SWITZERLAND);
    EnumBiMap<Currency, Country> bimap = EnumBiMap.create(map);

    Iterator<Currency> iter = bimap.keySet().iterator();
    assertEquals(Currency.DOLLAR, iter.next());