* order. The sorting algorithm used is stable, so elements that compare as equal will stay in the
   * order in which they appear in the input.
   *
   * <p>If your data has no duplicates, or you wish to deduplicate elements, use {@code
   * ImmutableSortedSet.copyOf(elements)}; if you want a {@code List} you can use its {@code
   * asList()} view.
   *

   * insertion order.
   */
  private void populateTShapedGraph() {
    putEdge(2, 1);
    putEdge(1, 4);
    putEdge(1, 3);
    putEdge(1, 2); // Duplicate
    putEdge(4, 5);
  }

  // Element Mutation

  @Test
  public void putEdge_existingNodes() {
    assume().that(graphIsMutable()).isTrue();

    checkNotNull(mergeFunction, "mergeFunction");

    /*
     * No mutable Table exactly matches the insertion order behavior of ImmutableTable.Builder, but
     * the Builder can't efficiently support merging of duplicate values.  Getting around this
     * requires some work.
     */

    return Collector.of(
        ImmutableTableCollectorState<R, C, V>::new,
        (state, input) ->
            state.put(

    Map<Integer, String> expected = new LinkedHashMap<>();
    for (int i = 0; i < 1000; i++) {
      // Truncate to even key, so we have put(0, "0") then put(0, "1"). Half the entries are
      // duplicates.
      Integer key = i & ~1;
      String value = String.valueOf(i);
      builder.put(key, value);
      expected.put(key, value);
    }
    ImmutableMap<Integer, String> map = builder.buildKeepingLast();

   *
   * @param anElement one of the elements the set should contain
   * @param otherElements the rest of the elements the set should contain
   * @return an immutable set containing those elements, minus duplicates
   */
  public static <E extends Enum<E>> ImmutableSet<E> immutableEnumSet(
      E anElement, E... otherElements) {
    return ImmutableEnumSet.asImmutable(EnumSet.of(anElement, otherElements));
  }

  /**

   * @param columnKeys column keys that may be stored in the generated table
   * @throws NullPointerException if any of the provided keys is null
   * @throws IllegalArgumentException if {@code rowKeys} or {@code columnKeys} contains duplicates
   *     or if exactly one of {@code rowKeys} or {@code columnKeys} is empty.
   */
  public static <R, C, V> ArrayTable<R, C, V> create(
      Iterable<? extends R> rowKeys, Iterable<? extends C> columnKeys) {

                if (field.getType().equals(HtmlNext.class)) {
                    HtmlNext htmlNext = (HtmlNext) field.get(null);
                    String path = htmlNext.getRoutingPath();
                    assertFalse("Duplicate path found: " + path + " in field " + field.getName(), paths.contains(path));
                    paths.add(path);
                }
            }
        }
        assertTrue("Should have unique paths", paths.size() > 0);

        return buf.toString().trim();
    }

    /**
     * Replaces duplicate hosts in the URL using the duplicate host helper.
     *
     * @param url the URL to process
     * @return the URL with duplicate hosts replaced
     */
    protected String replaceDuplicateHost(final String url) {
        try {
            // remove duplicate host

      default:
        return new RegularImmutableSet<E>(delegate);
    }
  }

  private static <E> ImmutableSet<E> create(E... elements) {
    // Create the set first, to remove duplicates if necessary.
    Set<E> set = Sets.newLinkedHashSet();
    Collections.addAll(set, elements);
    for (E element : set) {
      checkNotNull(element);
    }

    switch (set.size()) {
      case 0:

  }

  /**
   * {@inheritDoc}
   *
   * <p>The iterator generated by the returned collection traverses the values in the order they
   * were added to the multimap. Because the values may have duplicates and follow the insertion
   * ordering, this method returns a {@link List}, instead of the {@link Collection} specified in
   * the {@link ListMultimap} interface.
   */
  @Override
  public List<V> values() {