adder.accept(accumulator, SomeEnum.A);
    adder.accept(accumulator, SomeEnum.B);
    ImmutableSet<SomeEnum> set = collector.finisher().apply(accumulator);
    assertThat(set).containsExactly(SomeEnum.A, SomeEnum.B);

    // Subsequent manual manipulation of the accumulator must not affect the state of the built set
    adder.accept(accumulator, SomeEnum.C);

  private static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> fromEntries(
      Entry<K, V>... entries) {
    return fromEntries(Ordering.natural(), false, entries, entries.length);
  }

  /**
   * Accepts a collection of possibly-null entries. If {@code sameComparator}, then it is assumed
   * that they do not need to be sorted or checked for dupes.
   */
  private static <K, V> ImmutableSortedMap<K, V> fromEntries(

       * one as it is because one of our users has defined a wrapper API around Preconditions,
       * declaring a checkState method that accepts a possibly null template. So we'd need to update
       * that user first.
       */
      @CheckForNull String errorMessageTemplate,
      @CheckForNull @Nullable Object... errorMessageArgs) {
    if (!expression) {

  private static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> fromEntries(
      Entry<K, V>... entries) {
    return fromEntries(Ordering.natural(), false, entries, entries.length);
  }

  /**
   * Accepts a collection of possibly-null entries. If {@code sameComparator}, then it is assumed
   * that they do not need to be sorted or checked for dupes.
   */
  private static <K, V> ImmutableSortedMap<K, V> fromEntries(

          }
        };
    Map<String, String> transformed = transformEntries(options, flagPrefixer);
    assertEquals("{verbose=verbose, sort=nosort}", transformed.toString());
  }

  // Logically this would accept a NavigableMap, but that won't work under GWT.
  private static <K, V> SortedMap<K, V> sortedNotNavigable(final SortedMap<K, V> map) {
    return new ForwardingSortedMap<K, V>() {
      @Override

          }
        };
    Map<String, String> transformed = transformEntries(options, flagPrefixer);
    assertEquals("{verbose=verbose, sort=nosort}", transformed.toString());
  }

  // Logically this would accept a NavigableMap, but that won't work under GWT.
  private static <K, V> SortedMap<K, V> sortedNotNavigable(final SortedMap<K, V> map) {
    return new ForwardingSortedMap<K, V>() {
      @Override

  }

  private abstract static class RawTypeConsistencyTester<T extends Enum<T> & CharSequence> {
    abstract T returningT();

    abstract void acceptT(T t);

    abstract <X extends T> X returningX();

    abstract <X> void acceptX(X x);

    abstract <T2 extends Enum<T2> & CharSequence> T2 returningT2();

    abstract <T2 extends CharSequence & Iterable<T2>> void acceptT2(T2 t2);

      assertTrue(awaitUninterruptibly(returned, 10, SECONDS));
    }
  }

  static final class NoOpValueAndCloserConsumer<V> implements ValueAndCloserConsumer<V> {
    @Override
    public void accept(ValueAndCloser<V> valueAndCloser) {}
  }

  }

  /**
   * Returns a new, <i>mutable</i> {@code EnumSet} instance containing the given elements in their
   * natural order. This method behaves identically to {@link EnumSet#copyOf(Collection)}, but also
   * accepts non-{@code Collection} iterables and empty iterables.
   */
  public static <E extends Enum<E>> EnumSet<E> newEnumSet(
      Iterable<E> iterable, Class<E> elementType) {
    EnumSet<E> set = EnumSet.noneOf(elementType);

   * new stack trace matches that of the current thread.
   *
   * <p>Instances of {@code exceptionClass} are created by choosing an arbitrary public constructor
   * that accepts zero or more arguments, all of type {@code String} or {@code Throwable}
   * (preferring constructors with at least one {@code String}, then preferring constructors with at