*/
  protected abstract List<Character> create(Character[] elements);

  @Override
  public Character[] createArray(int length) {
    return new Character[length];
  }

  /** Returns the original element list, unchanged. */
  @Override
  public List<Character> order(List<Character> insertionOrder) {
    return insertionOrder;
  }

        assertTrue(stackTrace.length > 0);

        // Check that the current test method is in the stack trace
        boolean foundTestMethod = false;
        for (StackTraceElement element : stackTrace) {
            if (element.getMethodName().equals("test_stackTrace")) {
                foundTestMethod = true;
                break;
            }
        }
        assertTrue(foundTestMethod);
    }

        for (T input : inputs) {
          collector.accumulator().accept(accum, input);
        }
        return accum;
      }
    },
    /** Get one accumulator for each element and merge the accumulators left-to-right. */
    MERGE_LEFT_ASSOCIATIVE {
      @Override
      final <T extends @Nullable Object, A extends @Nullable Object, R extends @Nullable Object>

        assertTrue(stackTrace.length > 0);

        // Verify that the current test method appears in the stack trace
        boolean foundTestMethod = false;
        for (StackTraceElement element : stackTrace) {
            if (element.getMethodName().equals("test_stackTrace_isPresent")) {
                foundTestMethod = true;
                break;
            }
        }
        assertTrue(foundTestMethod);
    }

  @BeforeExperiment
  void setUp() throws Exception {
    Random r = new Random();
    ba1 = new byte[length];
    r.nextBytes(ba1);
    ba2 = Arrays.copyOf(ba1, ba1.length);
    // Differ at the last element
    ba3 = Arrays.copyOf(ba1, ba1.length);
    ba4 = Arrays.copyOf(ba1, ba1.length);
    ba3[ba1.length - 1] = (byte) 43;
    ba4[ba1.length - 1] = (byte) 42;

  @Param({"0", "1", "16", "256", "4096", "65536"})
  int size;

  LinkedHashMultiset<Object> linkedHashMultiset;
  HashMultiset<Object> hashMultiset;

  // TreeMultiset requires a Comparable element.
  TreeMultiset<Integer> treeMultiset;

  @BeforeExperiment
  void setUp() {
    hashMultiset = HashMultiset.create(size);
    linkedHashMultiset = LinkedHashMultiset.create(size);

    delegateFuture = (ScheduledFuture<?>) delegateQueue.element();
    assertTrue(delegateFuture.isCancelled());

    delegateQueue.clear();

    future = service.scheduleAtFixedRate(() -> {}, 5, 5, MINUTES);
    future.cancel(true);
    assertTrue(future.isCancelled());
    delegateFuture = (ScheduledFuture<?>) delegateQueue.element();
    assertTrue(delegateFuture.isCancelled());

  }

  public void testBroken() {
    Iterator<Object> broken = new BrokenAbstractSequentialIterator();
    assertTrue(broken.hasNext());
    // We can't retrieve even the known first element:
    assertThrows(SomeUncheckedException.class, broken::next);
    assertThrows(SomeUncheckedException.class, broken::next);
  }

  private static Iterator<Integer> newDoubler(int first, int last) {

  @Override
  @SuppressWarnings("unchecked") // generic arrays make typesafety sad
  public Entry<K, V>[] createArray(int length) {
    return (Entry<K, V>[]) new Entry<?, ?>[length];
  }

  /** Returns the original element list, unchanged. */
  @Override
  public List<Entry<K, V>> order(List<Entry<K, V>> insertionOrder) {
    return insertionOrder;
  }

    char[][] replacementArray = fem.getReplacementArray();
    // Array length is highest character value + 1
    assertThat(replacementArray).hasLength(65536);
    // The final element should always be non-null.
    assertThat(replacementArray[replacementArray.length - 1]).isNotNull();
    // Exhaustively check all mappings (an int index avoids wrapping).
    for (int n = 0; n < replacementArray.length; n++) {