assertEquals(string, readFully(reader));
    assertFullyRead(reader);

    // reset, skip, mark, then read the rest
    reader.reset();
    assertEquals(5, reader.skip(5));
    reader.mark(Integer.MAX_VALUE);
    assertEquals(string.substring(5), readFully(reader));
    assertFullyRead(reader);

    // reset to the mark and then read the rest
    reader.reset();
    assertEquals(string.substring(5), readFully(reader));

  static void clear(Buffer b) {
    b.clear();
  }

  static void flip(Buffer b) {
    b.flip();
  }

  static void limit(Buffer b, int limit) {
    b.limit(limit);
  }

  static void mark(Buffer b) {
    b.mark();
  }

  static void position(Buffer b, int position) {
    b.position(position);
  }

  static void reset(Buffer b) {
    b.reset();
  }

  private Java8Compatibility() {}

 * even when the result of the comparison is already known from previous {@code .compare} calls.
 * That can be expensive.
 *
 * @author Mark Davis
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ComparisonChain {
  private ComparisonChain() {}

        // subtracting two nonnegative longs can't overflow
        // cmpRemToHalfDivisor has the same sign as compare(abs(rem), abs(q) / 2).
        if (cmpRemToHalfDivisor == 0) { // exactly on the half mark
          increment = (mode == HALF_UP || (mode == HALF_EVEN && (div & 1) != 0));
        } else {
          increment = cmpRemToHalfDivisor > 0; // closer to the UP value
        }
        break;
      default:

    assertEquals(string, readFully(reader));
    assertFullyRead(reader);

    // reset, skip, mark, then read the rest
    reader.reset();
    assertEquals(5, reader.skip(5));
    reader.mark(Integer.MAX_VALUE);
    assertEquals(string.substring(5), readFully(reader));
    assertFullyRead(reader);

    // reset to the mark and then read the rest
    reader.reset();
    assertEquals(string.substring(5), readFully(reader));

    return true;
  }

  @Override
  public synchronized void mark(int readAheadLimit) throws IOException {
    checkArgument(readAheadLimit >= 0, "readAheadLimit (%s) may not be negative", readAheadLimit);
    checkOpen();
    mark = pos;
  }

  @Override
  public synchronized void reset() throws IOException {
    checkOpen();
    pos = mark;
  }

  @Override

    assertThat(expected).hasMessageThat().isEqualTo("Mark not set");
  }

  public void testMarkNotSupported() {
    counter = new CountingInputStream(new UnmarkableInputStream());

    IOException expected = assertThrows(IOException.class, () -> counter.reset());
    assertThat(expected).hasMessageThat().isEqualTo("Mark not supported");
  }

 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/CommonObjectUtilitiesExplained#comparecompareto">{@code
 * ComparisonChain}</a>.
 *
 * @author Mark Davis
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ComparisonChain {
  private ComparisonChain() {}

  /** Swappable internal implementation of an ImmutableSet.Builder. */
  private abstract static class SetBuilderImpl<E> {
    // The first `distinct` elements are non-null.
    // Since we can never access null elements, we don't mark this nullable.
    E[] dedupedElements;
    int distinct;

    @SuppressWarnings("unchecked")
    SetBuilderImpl(int expectedCapacity) {
      this.dedupedElements = (E[]) new Object[expectedCapacity];

    return get(key) != null;
  }

  @Override
  public boolean containsValue(@CheckForNull Object value) {
    return values().contains(value);
  }

  // Overriding to mark it Nullable
  @Override
  @CheckForNull
  public abstract V get(@CheckForNull Object key);

  /**
   * {@inheritDoc}
   *
   * <p>See <a