### Question:
DefaultEventCorrelator implements EventCorrelator { @Override public void received(String correlationId) { log.debug("received: {}", correlationId); remove(correlationId).ifPresent(future -> future.complete(null)); } DefaultEventCorrelator(); @Override String register(CompletableFuture<Void> future); @Override void received(String correlationId); @Override void failed(String correlationId, Exception e);  }### Answer:
@Test public void received() { var correlationId = underTest.register(future); underTest.received(correlationId); assertThat(futures.isEmpty(), is(true)); assertThat(future.isDone(), is(true)); }