@Nullable
  @Override
  // NULLSAFE_FIXME[Inconsistent Subclass Return Annotation]
  public List<Runnable> shutdownNow() {
    return null;
  }
Gets the underlying queue that backs the executor service.

@return the underlying queue
imagepipeline-base-test/src/main/java/com/facebook/imagepipeline/testing/TestExecutorService.java