public static class Chars extends SampleElements<Character> {
    public Chars() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super('b', 'a', 'c', 'd', 'e');
    }
  }

  public static class Enums extends SampleElements<AnEnum> {
    public Enums() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(AnEnum.B, AnEnum.A, AnEnum.C, AnEnum.D, AnEnum.E);
    }
  }

  public static class Chars extends SampleElements<Character> {
    public Chars() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super('b', 'a', 'c', 'd', 'e');
    }
  }

  public static class Enums extends SampleElements<AnEnum> {
    public Enums() {
      // elements aren't sorted, to better test SortedSet iteration ordering
      super(AnEnum.B, AnEnum.A, AnEnum.C, AnEnum.D, AnEnum.E);
    }
  }

   * stream is empty.
   *
   * <p>Equivalent to {@code stream.reduce((a, b) -> b)}, but may perform significantly better. This
   * method's runtime will be between O(log n) and O(n), performing better on <a
   * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>
   * streams.
   *

   * stream is empty.
   *
   * <p>Equivalent to {@code stream.reduce((a, b) -> b)}, but may perform significantly better. This
   * method's runtime will be between O(log n) and O(n), performing better on <a
   * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>
   * streams.
   *

    assertEquals(c, navigableSet.higher(b));
    assertEquals(null, navigableSet.higher(c));
  }

  /*
   * TODO(cpovirk): make "too small" and "too large" elements available for better navigation
   * testing. At that point, we may be able to eliminate the "hole" tests, which would mean that
   * ContiguousSet's tests would no longer need to suppress them.
   */
  @CollectionSize.Require(SEVERAL)

    assertEquals(c, navigableSet.higher(b));
    assertEquals(null, navigableSet.higher(c));
  }

  /*
   * TODO(cpovirk): make "too small" and "too large" elements available for better navigation
   * testing. At that point, we may be able to eliminate the "hole" tests, which would mean that
   * ContiguousSet's tests would no longer need to suppress them.
   */
  @CollectionSize.Require(SEVERAL)

    return !disjoint(a, b);
  }

  private static Method extractMethod(Test test) {
    if (test instanceof AbstractTester) {
      AbstractTester<?> tester = (AbstractTester<?>) test;
      return getMethod(tester.getClass(), tester.getTestMethodName());
    } else if (test instanceof TestCase) {
      TestCase testCase = (TestCase) test;
      return getMethod(testCase.getClass(), testCase.getName());

          SpliteratorDecompositionStrategy.ALL_STRATEGIES) {
        List<E> resultsForStrategy = new ArrayList<>();
        strategy.forEach(spliteratorSupplier.get(), resultsForStrategy::add);

        // TODO(cpovirk): better failure messages
        if ((characteristics & Spliterator.NONNULL) != 0) {
          assertFalse(resultsForStrategy.contains(null));
        }
        if ((characteristics & Spliterator.SORTED) != 0) {

          SpliteratorDecompositionStrategy.ALL_STRATEGIES) {
        List<E> resultsForStrategy = new ArrayList<>();
        strategy.forEach(spliteratorSupplier.get(), resultsForStrategy::add);

        // TODO(cpovirk): better failure messages
        if ((characteristics & Spliterator.NONNULL) != 0) {
          assertFalse(resultsForStrategy.contains(null));
        }
        if ((characteristics & Spliterator.SORTED) != 0) {

                requireNonNull(e2);
                return comparator.compare(e1.getKey(), e2.getKey());
              });
          // requireNonNull is safe because the first `size` elements have been filled in.
          Entry<K, V> firstEntry = requireNonNull(entryArray[0]);
          K prevKey = firstEntry.getKey();
          keys[0] = prevKey;
          values[0] = firstEntry.getValue();