if ((coreExtensions.getExtensions() != null)
                && (coreExtensions.getExtensions().size() > 0)) {
            for (Iterator iter = coreExtensions.getExtensions().iterator(); iter.hasNext(); ) {
                CoreExtension o = (CoreExtension) iter.next();
                writeCoreExtension(o, "extension", serializer);
            }
        }

  private int position;

  /** Returns the element with the specified index. This method is called by {@link #next()}. */
  @ParametricNullness
  protected abstract E get(int index);

  /**
   * Constructs an iterator across a sequence of the given size whose initial position is 0. That
   * is, the first call to {@link #next()} will return the first element (or throw {@link
   * NoSuchElementException} if {@code size} is zero).
   *

  }

  /**
   * Returns a sequential {@link Stream} of the remaining contents of {@code iterator}. Do not use
   * {@code iterator} directly after passing it to this method.
   */
  public static <T extends @Nullable Object> Stream<T> stream(Iterator<T> iterator) {
    return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, 0), false);
  }

  /**

        if (r1.size() != r2.size()) {
            return false;
        }

        for (Iterator<ArtifactRepository> it1 = r1.iterator(), it2 = r2.iterator(); it1.hasNext(); ) {
            if (!repositoryEquals(it1.next(), it2.next())) {
                return false;
            }
        }

        return true;
    }

    }
    return builder.build();
  }

  ImmutableMultiset() {}

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

      @Override
      public boolean hasNext() {

        result = size = Ints.saturatedCast(total);
      }
      return result;
    }

    @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()) {

    map.putInstance(String.class, "test");
    assertEquals(TypeToken.of(String.class), map.entrySet().iterator().next().getKey());
    assertEquals("test", map.entrySet().iterator().next().getValue());
    assertThrows(
        UnsupportedOperationException.class, () -> map.entrySet().iterator().next().setValue(1));
  }

  public void testEntrySetToArrayMutationThrows() {
    map.putInstance(String.class, "test");

    IncidentEdgeSet<N> incident =
        new IncidentEdgeSet<N>(this, node, IncidentEdgeSet.EdgeType.BOTH) {
          @Override
          public Iterator<EndpointPair<N>> iterator() {
            return connections.incidentEdgeIterator(node);
          }
        };
    return nodeInvalidatableSet(incident, node);
  }

  @Override

        result = size = Ints.saturatedCast(total);
      }
      return result;
    }

    @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()) {

        () -> {
          Iterator<String> iterator = values.iterator();
          iterator.next();
          iterator.remove();
        });

    Set<Entry<Integer, String>> entries = unmod.entrySet();
    assertThrows(
        UnsupportedOperationException.class,
        () -> {
          Iterator<Entry<Integer, String>> iterator = entries.iterator();
          iterator.next();