public void testGenerics() {
    ListMultimap<String, Integer> unusedA = MultimapBuilder.hashKeys().arrayListValues().build();
    SortedSetMultimap<String, Integer> unusedB =
        MultimapBuilder.linkedHashKeys().treeSetValues().build();
    SetMultimap<String, Integer> unusedC =
        MultimapBuilder.treeKeys(String.CASE_INSENSITIVE_ORDER).hashSetValues().build();
  }

  public void testGenerics_gwtCompatible() {

        flatteningToMultimap(
            input -> checkNotNull(keyFunction.apply(input)),
            input -> valuesFunction.apply(input).peek(Preconditions::checkNotNull),
            MultimapBuilder.linkedHashKeys().arrayListValues()::<K, V>build),
        ImmutableListMultimap::copyOf);
  }

  static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(

        flatteningToMultimap(
            input -> checkNotNull(keyFunction.apply(input)),
            input -> valuesFunction.apply(input).peek(Preconditions::checkNotNull),
            MultimapBuilder.linkedHashKeys().arrayListValues()::<K, V>build),
        ImmutableListMultimap::copyOf);
  }

  static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(

   * back into the multimap, that key will come last in the key iteration order.
   */
  public static MultimapBuilderWithKeys<@Nullable Object> linkedHashKeys() {
    return linkedHashKeys(DEFAULT_EXPECTED_KEYS);
  }

  /**
   * Uses an hash table to map keys to value collections, initialized to expect the specified number
   * of keys.
   *

   * back into the multimap, that key will come last in the key iteration order.
   */
  public static MultimapBuilderWithKeys<@Nullable Object> linkedHashKeys() {
    return linkedHashKeys(DEFAULT_EXPECTED_KEYS);
  }

  /**
   * Uses an hash table to map keys to value collections, initialized to expect the specified number
   * of keys.
   *

   *                  MultimapBuilder.linkedHashKeys().arrayListValues()::build));
   *
   * // is equivalent to
   *
   * static final ListMultimap<Character, Character> FIRST_LETTER_MULTIMAP;
   *
   * static {
   *     FIRST_LETTER_MULTIMAP = MultimapBuilder.linkedHashKeys().arrayListValues().build();

   *                  MultimapBuilder.linkedHashKeys().arrayListValues()::build));
   *
   * // is equivalent to
   *
   * static final ListMultimap<Character, Character> FIRST_LETTER_MULTIMAP;
   *
   * static {
   *     FIRST_LETTER_MULTIMAP = MultimapBuilder.linkedHashKeys().arrayListValues().build();