code: public void awaitTermination() {
          try {
              latch.await();
          } catch (InterruptedException e) {
              String message = "awaitTermination() method was interrupted!";
              throw new UnsupportedOperationException(message, e);
          }
      }
docs: Blocks until the last poll-cycle has finished and all {@link AfterStopEvent} has been
  processed.