*/
  public static Ticker systemTicker() {
    return SYSTEM_TICKER;
  }

  private static final Ticker SYSTEM_TICKER =
      new Ticker() {
        @Override
        @SuppressWarnings("GoodTime") // reading system time without TimeSource
        public long read() {
          return System.nanoTime();
        }
      };

    assertEquals(20, counter.skip(30));
    assertEquals(20, counter.getCount());
    assertEquals(0, counter.skip(20));
    assertEquals(20, counter.getCount());

    // Test reading a single byte while we're in the right state
    assertEquals(-1, counter.read());
    assertEquals(20, counter.getCount());
  }

  public void testReadArrayEOF() throws IOException {

    stream.writeObject(valueComparator());
    Serialization.writeMultimap(this, stream);
  }

  @GwtIncompatible // java.io.ObjectInputStream
  @J2ktIncompatible
  @SuppressWarnings("unchecked") // reading data stored by writeObject
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();

/**
 * An object that accurately measures <i>elapsed time</i>: the measured duration between two
 * successive readings of "now" in the same process.
 *
 * <p>In contrast, <i>wall time</i> is a reading of "now" as given by a method like
 * {@link System#currentTimeMillis()}, best represented as an {@link java.time.Instant}. Such values
 * <i>can</i> be subtracted to obtain a {@code Duration} (such as by {@code Duration.between}), but

   * to reduce cache contention on most processors. Padding is
   * overkill for most Atomics because they are usually irregularly
   * scattered in memory and thus don't interfere much with each
   * other. But Atomic objects residing in arrays will tend to be
   * placed adjacent to each other, and so will most often share
   * cache lines (with a huge negative performance impact) without
   * this precaution.
   *

      stream.defaultWriteObject();
      stream.writeObject(inverse());
    }

    @GwtIncompatible // java.io.ObjectInputStream
    @J2ktIncompatible
    @SuppressWarnings("unchecked") // reading data stored by writeObject
    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
      stream.defaultReadObject();

    // Append 10 more bytes to the source.
    source.append(newPreFilledByteArray(5, 10));

    // The stream reports no bytes... importantly, it doesn't read the byte at index 5 when it
    // should be reading the byte at index 10.
    // We could use a custom InputStream instead to make the read start at index 10, but since this
    // is a racy situation anyway, this behavior seems reasonable.
    assertEquals(-1, in.read());
  }

  }

  @J2ktIncompatible // serialization
  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
    @SuppressWarnings("unchecked") // reading data stored by writeObject
    ConcurrentMap<E, Integer> deserializedCountMap =
        (ConcurrentMap<E, Integer>) requireNonNull(stream.readObject());

   * than would be returned by reading all of the bytes (for example, some special files may return
   * a size of 0 despite actually having content when read).
   *
   * <p>In either case, for mutable sources such as files, a subsequent read may return a different
   * number of bytes if the contents are changed.
   *
   * @throws IOException if an I/O error occurs while reading the size of this source
   */

   * than would be returned by reading all of the chars.
   *
   * <p>In either case, for mutable sources such as files, a subsequent read may return a different
   * number of chars if the contents are changed.
   *
   * @throws IOException if an I/O error occurs while reading the length of this source
   * @since 19.0
   */
  public long length() throws IOException {