* versions.
   */
  public static Stats fromByteArray(byte[] byteArray) {
    checkNotNull(byteArray);
    checkArgument(
        byteArray.length == BYTES,
        "Expected Stats.BYTES = %s remaining , got %s",
        BYTES,
        byteArray.length);
    return readFrom(ByteBuffer.wrap(byteArray).order(ByteOrder.LITTLE_ENDIAN));
  }

  /**

    assertEquals(1, stats.hitCount());
    assertEquals(1.0 / 2, stats.hitRate());
    assertEquals(1, stats.missCount());
    assertEquals(1.0 / 2, stats.missRate());
    assertEquals(1, stats.loadCount());
    assertEquals(0, stats.evictionCount());

    Object two = new Object();
    cache.getUnchecked(two);
    stats = cache.stats();
    assertEquals(3, stats.requestCount());

        // this getUnchecked() call shouldn't be a cache miss; verified below
        assertEquals(entry.getValue(), cache.getUnchecked(entry.getKey()));
      }
      assertEquals(WARMUP_SIZE, cache.stats().missCount());
      checkValidState(cache);
    }
  }

  public void testPut_populated() {
    for (LoadingCache<Object, Object> cache : caches()) {
      // don't let the entries get GCed

  }

  public void testSize() {
    when(mock.size()).thenReturn(0L);
    assertEquals(0, forward.size());
  }

  public void testStats() {
    when(mock.stats()).thenReturn(null);
    assertNull(forward.stats());
  }

  public void testAsMap() {
    when(mock.asMap()).thenReturn(null);
    assertNull(forward.asMap());
  }

  public void testCleanUp() {
    forward.cleanUp();

    stats = cache.stats();
    assertEquals(2, stats.missCount());
    assertEquals(3, stats.loadSuccessCount());
    assertEquals(0, stats.loadExceptionCount());
    assertEquals(0, stats.hitCount());

    assertSame(key, cache.get(key));
    stats = cache.stats();
    assertEquals(2, stats.missCount());
    assertEquals(3, stats.loadSuccessCount());
    assertEquals(0, stats.loadExceptionCount());

  public void invalidateAll() {
    delegate().invalidateAll();
  }

  @Override
  public long size() {
    return delegate().size();
  }

  @Override
  public CacheStats stats() {
    return delegate().stats();
  }

  @Override
  public ConcurrentMap<K, V> asMap() {
    return delegate().asMap();
  }

  @Override
  public void cleanUp() {
    delegate().cleanUp();
  }

  public void invalidateAll() {
    delegate().invalidateAll();
  }

  @Override
  public long size() {
    return delegate().size();
  }

  @Override
  public CacheStats stats() {
    return delegate().stats();
  }

  @Override
  public ConcurrentMap<K, V> asMap() {
    return delegate().asMap();
  }

  @Override
  public void cleanUp() {
    delegate().cleanUp();
  }

    assertStatsApproxEqual(TWO_VALUES_STATS, TWO_VALUES_PAIRED_STATS.xStats());
    assertStatsApproxEqual(MANY_VALUES_STATS_ITERABLE, MANY_VALUES_PAIRED_STATS.xStats());
  }

  public void testYStats() {
    assertStatsApproxEqual(EMPTY_STATS_ITERABLE, EMPTY_PAIRED_STATS.yStats());
    assertStatsApproxEqual(OTHER_ONE_VALUE_STATS, ONE_VALUE_PAIRED_STATS.yStats());

    assertStatsApproxEqual(TWO_VALUES_STATS, TWO_VALUES_PAIRED_STATS.xStats());
    assertStatsApproxEqual(MANY_VALUES_STATS_ITERABLE, MANY_VALUES_PAIRED_STATS.xStats());
  }

  public void testYStats() {
    assertStatsApproxEqual(EMPTY_STATS_ITERABLE, EMPTY_PAIRED_STATS.yStats());
    assertStatsApproxEqual(OTHER_ONE_VALUE_STATS, ONE_VALUE_PAIRED_STATS.yStats());

    Stats stats = Stats.of(megaPrimitiveDoubleStream());
    assertThat(stats.count()).isEqualTo(MEGA_STREAM_COUNT);
    assertThat(stats.mean()).isWithin(ALLOWED_ERROR * MEGA_STREAM_COUNT).of(MEGA_STREAM_MEAN);
    assertThat(stats.populationVariance())
        .isWithin(ALLOWED_ERROR * MEGA_STREAM_COUNT)
        .of(MEGA_STREAM_POPULATION_VARIANCE);
    assertThat(stats.min()).isEqualTo(MEGA_STREAM_MIN);