public void testCopyOf_collectionContainingNull() {
    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");
    assertThrows(NullPointerException.class, () -> copyOf((Collection<String>) c));
  }

  enum TestEnum {
    A,
    B,
    C,
    D
  }

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

      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,

      }
      ImmutableDoubleArray iia = builder.build();
      for (int j = 0; j < iia.length(); j++) {
        assertThat(iia.get(j)).isEqualTo((double) j);
      }
    }
  }

  private enum BuilderOp {
    ADD_ONE {
      @Override
      void doIt(ImmutableDoubleArray.Builder builder, AtomicInteger counter) {
        builder.add(counter.getAndIncrement());
      }
    },
    ADD_ARRAY {

      }
      ImmutableDoubleArray iia = builder.build();
      for (int j = 0; j < iia.length(); j++) {
        assertThat(iia.get(j)).isEqualTo((double) j);
      }
    }
  }

  private enum BuilderOp {
    ADD_ONE {
      @Override
      void doIt(ImmutableDoubleArray.Builder builder, AtomicInteger counter) {
        builder.add(counter.getAndIncrement());
      }
    },
    ADD_ARRAY {

   * char[])}.
   *
   * @since 2.0
   */
  public static Comparator<char[]> lexicographicalComparator() {
    return LexicographicalComparator.INSTANCE;
  }

  private enum LexicographicalComparator implements Comparator<char[]> {
    INSTANCE;

    @Override
    public int compare(char[] left, char[] right) {
      int minLength = Math.min(left.length, right.length);

   * short[])}.
   *
   * @since 2.0
   */
  public static Comparator<short[]> lexicographicalComparator() {
    return LexicographicalComparator.INSTANCE;
  }

  private enum LexicographicalComparator implements Comparator<short[]> {
    INSTANCE;

    @Override
    public int compare(short[] left, short[] right) {
      int minLength = Math.min(left.length, right.length);

      if (newArg == null || Objects.equals(args.get(i), newArg)) {
        if (params.get(i).getType().getRawType().isEnum()) {
          continue; // Nothing better we can do if it's single-value enum
        }
        throw new ParameterHasNoDistinctValueException(params.get(i));
      }
      newArgs.set(i, newArg);
      tester.addEqualityGroup(createInstance(factory, newArgs));

   * short[])}.
   *
   * @since 2.0
   */
  public static Comparator<short[]> lexicographicalComparator() {
    return LexicographicalComparator.INSTANCE;
  }

  private enum LexicographicalComparator implements Comparator<short[]> {
    INSTANCE;

    @Override
    public int compare(short[] left, short[] right) {
      int minLength = Math.min(left.length, right.length);

  };

  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

        }
    }

    /**
     * Enumeration of different artifact types supported by Fess.
     * Each type has a specific ID prefix used to identify artifacts of that type.
     */
    public enum ArtifactType {
        /** Data store plugins */
        DATA_STORE("fess-ds"), //
        /** Theme plugins */
        THEME("fess-theme"), //
        /** Ingest processor plugins */