.put(CharSink.class, NullByteSink.INSTANCE.asCharSink(UTF_8))
          // All collections are immutable empty. So safe for any type parameter.
          .put(Iterator.class, ImmutableSet.of().iterator())
          .put(PeekingIterator.class, Iterators.peekingIterator(ImmutableSet.of().iterator()))
          .put(ListIterator.class, ImmutableList.of().listIterator())
          .put(Iterable.class, ImmutableSet.of())

    Iterator<String> iterator = asList("a", "b", "a").iterator();
    Multiset<String> multiset = ImmutableMultiset.copyOf(iterator);
    assertEquals(HashMultiset.create(asList("a", "b", "a")), multiset);
  }

  public void testCopyOf_iteratorContainingNull() {
    Iterator<@Nullable String> iterator =
        Arrays.<@Nullable String>asList("a", null, "b").iterator();
    assertThrows(

   * the map directly affect the cache.
   *
   * <p>Iterators from the returned map are at least <i>weakly consistent</i>: they are safe for
   * concurrent use, but if the cache is modified (including by eviction) after the iterator is
   * created, it is undefined which of the changes (if any) will be reflected in that iterator.
   *

    Iterator<String> iterator = asList("a", "b", "a").iterator();
    List<String> list = ImmutableList.copyOf(iterator);
    assertEquals(asList("a", "b", "a"), list);
  }

  public void testCopyOf_iteratorContainingNull() {
    Iterator<@Nullable String> iterator =
        Arrays.<@Nullable String>asList("a", null, "b").iterator();
    assertThrows(

      }
    }
    size--;
  }

  /** Removes all nodes for the specified key. */
  private void removeAllNodes(@ParametricNullness K key) {
    Iterators.clear(new ValueForKeyIterator(key));
  }

  /** An {@code Iterator} over all nodes. */
  private final class NodeIterator implements ListIterator<Entry<K, V>> {
    int nextIndex;
    @Nullable Node<K, V> next;
    @Nullable Node<K, V> current;

    Iterator<String> iterator = asList("a", "b", "a").iterator();
    List<String> list = ImmutableList.copyOf(iterator);
    assertEquals(asList("a", "b", "a"), list);
  }

  public void testCopyOf_iteratorContainingNull() {
    Iterator<@Nullable String> iterator =
        Arrays.<@Nullable String>asList("a", null, "b").iterator();
    assertThrows(

      }
      return result.intValue();
    }

    @Override
    public UnmodifiableIterator<C> iterator() {
      return new AbstractIterator<C>() {
        final Iterator<Range<C>> rangeItr = ranges.iterator();
        Iterator<C> elemItr = emptyIterator();

        @Override
        protected @Nullable C computeNext() {
          while (!elemItr.hasNext()) {

    @Override
    public Set<EndpointPair<N>> incidentEdges(N node) {
      return new IncidentEdgeSet<N>(this, node) {
        @Override
        public Iterator<EndpointPair<N>> iterator() {
          return Iterators.transform(
              delegate().incidentEdges(node).iterator(),
              edge -> EndpointPair.of(delegate(), edge.nodeV(), edge.nodeU()));
        }
      };
    }

    @Override

    @Override
    public Set<EndpointPair<N>> incidentEdges(N node) {
      return new IncidentEdgeSet<N>(this, node) {
        @Override
        public Iterator<EndpointPair<N>> iterator() {
          return Iterators.transform(
              delegate().incidentEdges(node).iterator(),
              edge -> EndpointPair.of(delegate(), edge.nodeV(), edge.nodeU()));
        }
      };
    }

    @Override

          return AsMap.this;
        }

        @Override
        public Iterator<Entry<K, Collection<V>>> iterator() {
          return new AbstractIterator<Entry<K, Collection<V>>>() {
            final Iterator<Entry<K, Collection<V>>> backingIterator =
                unfiltered.asMap().entrySet().iterator();

            @Override
            protected @Nullable Entry<K, Collection<V>> computeNext() {