@Override
  public boolean isRegisterByteSizeObserverCheap(T value) {
    return windowCoder.isRegisterByteSizeObserverCheap(value);
  }
@Test
  public void testIsRegisterByteSizeObserverCheap() {
    TimestampPrefixingWindowCoder<CustomWindow> coder1 =
        TimestampPrefixingWindowCoder.of(CustomWindowCoder.of(true, true));
    assertThat(coder1.isRegisterByteSizeObserverCheap(CUSTOM_WINDOW_LIST.get(0)), equalTo(true));
    TimestampPrefixingWindowCoder<CustomWindow> coder2 =
        TimestampPrefixingWindowCoder.of(CustomWindowCoder.of(true, false));
    assertThat(coder2.isRegisterByteSizeObserverCheap(CUSTOM_WINDOW_LIST.get(0)), equalTo(false));
  }