@Override
  public @Nullable Instant currentSynchronizedProcessingTime() {
    return watermarks.getSynchronizedProcessingInputTime();
  }
@Test
  public void getSynchronizedProcessingTimeIsWatermarkSynchronizedInputTime() {
    when(watermarks.getSynchronizedProcessingInputTime()).thenReturn(new Instant(12345L));
    assertThat(internals.currentSynchronizedProcessingTime(), equalTo(new Instant(12345L)));
  }