shouldFail(instance, Visibility.PROTECTED);
    shouldFail(instance, Visibility.PUBLIC);
  }

  private static void shouldFail(Class<?> cls, Visibility visibility) {
    try {
      new NullPointerTester().testStaticMethods(cls, visibility);
    } catch (AssertionError expected) {
      return;
    }
    fail("Should detect problem in " + cls.getSimpleName());
  }

  private static void shouldFail(Class<?> cls) {

  static final class DelayingIdentityLoader<T> extends CacheLoader<T, T> {
    private final AtomicBoolean shouldWait;
    private final CountDownLatch delayLatch;

    DelayingIdentityLoader(AtomicBoolean shouldWait, CountDownLatch delayLatch) {
      this.shouldWait = shouldWait;
      this.delayLatch = delayLatch;
    }

    @CanIgnoreReturnValue // Sure, why not?
    @Override

  static final class DelayingIdentityLoader<T> extends CacheLoader<T, T> {
    private final AtomicBoolean shouldWait;
    private final CountDownLatch delayLatch;

    DelayingIdentityLoader(AtomicBoolean shouldWait, CountDownLatch delayLatch) {
      this.shouldWait = shouldWait;
      this.delayLatch = delayLatch;
    }

    @CanIgnoreReturnValue // Sure, why not?
    @Override