List<E> elements = new ArrayList<>();
      Helpers.addAll(elements, previousElements);
      Helpers.addAll(elements, Helpers.reverse(nextElements));
      return elements;
    }
  }

  public enum KnownOrder {
    KNOWN_ORDER,
    UNKNOWN_ORDER
  }

  @SuppressWarnings("unchecked") // TODO(cpovirk): Stop using arrays.
  AbstractIteratorTester(
      int steps,

    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");
    try {
      copyOf((Collection<String>) c);
      fail();
    } catch (NullPointerException expected) {
    }
  }

  enum TestEnum {
    A,
    B,
    C,
    D
  }

  public void testCopyOf_collection_enumSet() {
    Collection<TestEnum> c = EnumSet.of(TestEnum.A, TestEnum.B, TestEnum.D);

    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");
    try {
      copyOf((Collection<String>) c);
      fail();
    } catch (NullPointerException expected) {
    }
  }

  enum TestEnum {
    A,
    B,
    C,
    D
  }

  public void testCopyOf_collection_enumSet() {
    Collection<TestEnum> c = EnumSet.of(TestEnum.A, TestEnum.B, TestEnum.D);

  };

  private enum MillerRabinTester {
    /** Works for inputs ≤ FLOOR_SQRT_MAX_LONG. */
    SMALL {
      @Override
      long mulMod(long a, long b, long m) {
        /*
         * lowasser, 2015-Feb-12: Benchmarks suggest that changing this to UnsignedLongs.remainder
         * and increasing the threshold to 2^32 doesn't pay for itself, and adding another enum

    this.header = new AvlNode<>();
    successor(header, header);
    this.rootReference = new Reference<>();
  }

  /** A function which can be summed across a subtree. */
  private enum Aggregate {
    SIZE {
      @Override
      int nodeAggregate(AvlNode<?> node) {
        return node.elemCount;
      }

      @Override
      long treeAggregate(@CheckForNull AvlNode<?> root) {

   *
   * @since 14.0
   */
  public static HashFunction adler32() {
    return ChecksumType.ADLER_32.hashFunction;
  }

  @Immutable
  enum ChecksumType implements ImmutableSupplier<Checksum> {
    CRC_32("Hashing.crc32()") {
      @Override
      public Checksum get() {
        return new CRC32();
      }
    },
    ADLER_32("Hashing.adler32()") {

   * {@code enumClass} using {@link Enum#valueOf(Class, String)} and {@link Enum#name()}. The
   * converter will throw an {@code IllegalArgumentException} if the argument is not the name of any
   * enum constant in the specified enum.
   *
   * @since 16.0
   */
  @GwtIncompatible
  public static <T extends Enum<T>> Converter<String, T> stringConverter(Class<T> enumClass) {

      }
    };
  }

  enum QueueImpl implements CollectionsImplEnum {
    MinMaxPriorityQueueImpl {
      @Override
      public <E extends Comparable<E>> Queue<E> create(Collection<E> contents) {
        return MinMaxPriorityQueue.create(contents);
      }
    };
  }

  enum TableImpl {
    HashBasedTableImpl {
      @Override

      }
    };
  }

  enum QueueImpl implements CollectionsImplEnum {
    MinMaxPriorityQueueImpl {
      @Override
      public <E extends Comparable<E>> Queue<E> create(Collection<E> contents) {
        return MinMaxPriorityQueue.create(contents);
      }
    };
  }

  enum TableImpl {
    HashBasedTableImpl {
      @Override

@J2ktIncompatible
@ElementTypesAreNonnullByDefault
public final class EnumMultiset<E extends Enum<E>> extends AbstractMapBasedMultiset<E>
    implements Serializable {
  public static <E extends Enum<E>> EnumMultiset<E> create(Class<E> type) {
    return new EnumMultiset<>(new EnumMap<E, Count>(type));
  }

  public static <E extends Enum<E>> EnumMultiset<E> create(Iterable<E> elements) {
    Iterator<E> iterator = elements.iterator();