public static <K, V> Cache<K, V> noop() {
    return forMaximumBytes(0L);
  }
@Test
  public void testNoopCache() throws Exception {
    Cache<String, String> cache = Caches.noop();
    cache.put("key", "value");
    assertNull(cache.peek("key"));
    assertEquals("value", cache.computeIfAbsent("key", (unused) -> "value"));
    assertNull(cache.peek("key"));
  }