int left = 0;
    int right = 2 * k - 1;

    int minThresholdPosition = 0;
    // The leftmost position at which the greatest of the k lower elements
    // -- the new value of threshold -- might be found.

    int iterations = 0;
    int maxIterations = IntMath.log2(right - left, RoundingMode.CEILING) * 3;
    while (left < right) {
      int pivotIndex = (left + right + 1) >>> 1;

      successor(pred(), succ());
      if (left == null) {
        return right;
      } else if (right == null) {
        return left;
      } else if (left.height >= right.height) {
        AvlNode<E> newTop = pred();
        // newTop is the maximum node in my left subtree
        newTop.left = left.removeMax(newTop);
        newTop.right = right;
        newTop.distinctElements = distinctElements - 1;

    MapDifference<Integer, String> original = Maps.difference(left, right);
    MapDifference<Integer, String> same = Maps.difference(left, right);
    MapDifference<Integer, String> reverse = Maps.difference(right, left);
    MapDifference<Integer, String> diff2 = Maps.difference(left, right2);

    new EqualsTester()
        .addEqualityGroup(original, same)
        .addEqualityGroup(reverse)
        .addEqualityGroup(diff2)

    MapDifference<Integer, String> original = Maps.difference(left, right);
    MapDifference<Integer, String> same = Maps.difference(left, right);
    MapDifference<Integer, String> reverse = Maps.difference(right, left);
    MapDifference<Integer, String> diff2 = Maps.difference(left, right2);

    new EqualsTester()
        .addEqualityGroup(original, same)
        .addEqualityGroup(reverse)
        .addEqualityGroup(diff2)

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Integer[] concat(Integer[] left, Integer[] right) {
    Integer[] result = new Integer[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

  public abstract static class TestIntegerListGenerator implements TestListGenerator<Integer> {

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Byte[] concat(Byte[] left, Byte[] right) {
    Byte[] result = new Byte[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

  public abstract static class TestByteListGenerator implements TestListGenerator<Byte> {

          accum = collector.combiner().apply(accum, newAccum);
        }
        return accum;
      }
    },
    /** Get one accumulator for each element and merge the accumulators right-to-left. */
    MERGE_RIGHT_ASSOCIATIVE {
      @Override
      final <T extends @Nullable Object, A extends @Nullable Object, R extends @Nullable Object>
          A result(Collector<T, A, R> collector, Iterable<T> inputs) {

      return asList(all).subList(2, elements.length + 2);
    }
  }

  private static Long[] concat(Long[] left, Long[] right) {
    Long[] result = new Long[left.length + right.length];
    System.arraycopy(left, 0, result, 0, left.length);
    System.arraycopy(right, 0, result, left.length, right.length);
    return result;
  }

  public abstract static class TestLongListGenerator implements TestListGenerator<Long> {

      return new Ordering<Entry<String, Integer>>() {
        @Override
        public int compare(Entry<String, Integer> left, Entry<String, Integer> right) {
          return left.getKey().compareTo(right.getKey());
        }
      }.sortedCopy(insertionOrder);
    }

    @Override
    public List<Entry<String, Integer>> create(Object... elements) {

                      public int compare(Entry<String, String> left, Entry<String, String> right) {
                        return ComparisonChain.start()
                            .compare(left.getKey(), right.getKey(), Ordering.natural().nullsFirst())
                            .compare(
                                left.getValue(), right.getValue(), Ordering.natural().nullsFirst())
                            .result();