public void run() {
        cache.refresh(refreshKey);
        getFinishedSignal.countDown();
      }
    }.start();

    computationStarted.await();
    cache.invalidate(getKey);
    cache.invalidate(refreshKey);
    assertFalse(map.containsKey(getKey));
    assertFalse(map.containsKey(refreshKey));

    // let computation complete
    letGetFinishSignal.countDown();

   */

  /**
   * Ensures that an object reference passed as a parameter to the calling method is not null.
   *
   * @param reference an object reference
   * @return the non-null reference that was validated
   * @throws NullPointerException if {@code reference} is null
   * @see Verify#verifyNotNull Verify.verifyNotNull()
   */
  @CanIgnoreReturnValue
  public static <T> T checkNotNull(@Nullable T reference) {

* Kubelet: Start using the official docker engine-api ([#23506](https://github.com/kubernetes/kubernetes/pull/23506), [@Random-Liu](https://github.com/Random-Liu))
* Fix so setup-files don't recreate/invalidate certificates that already exist ([#23550](https://github.com/kubernetes/kubernetes/pull/23550), [@luxas](https://github.com/luxas))