*/
  public abstract V load(K key) throws Exception;

  /**
   * Computes or retrieves a replacement value corresponding to an already-cached {@code key}. This
   * method is called when an existing cache entry is refreshed by {@link
   * CacheBuilder#refreshAfterWrite}, or through a call to {@link LoadingCache#refresh}.
   *
   * <p>This implementation synchronously delegates to {@link #load}. It is recommended that it be

    assertEquals(0, stats.loadExceptionCount());
    assertEquals(1, stats.hitCount());

    ticker.advance(1, MILLISECONDS);
    assertSame(one, cache.getUnchecked(key));
    // refreshed
    stats = cache.stats();
    assertEquals(1, stats.missCount());
    assertEquals(1, stats.loadSuccessCount());
    assertEquals(1, stats.loadExceptionCount());
    assertEquals(2, stats.hitCount());

    assertEquals(0, stats.loadExceptionCount());
    assertEquals(1, stats.hitCount());

    ticker.advance(1, MILLISECONDS);
    assertSame(one, cache.getUnchecked(key));
    // refreshed
    stats = cache.stats();
    assertEquals(1, stats.missCount());
    assertEquals(1, stats.loadSuccessCount());
    assertEquals(1, stats.loadExceptionCount());
    assertEquals(2, stats.hitCount());

      }
      return oldValue;
    }

    /**
     * Refreshes the value associated with {@code key}, unless another thread is already doing so.
     * Returns the newly refreshed value associated with {@code key} if it was refreshed inline, or
     * {@code null} if another thread is performing the refresh or if an error occurs during
     * refresh.
     */
    @CanIgnoreReturnValue
    @CheckForNull

   */
  public abstract V load(K key) throws Exception;

  /**
   * Computes or retrieves a replacement value corresponding to an already-cached {@code key}. This
   * method is called when an existing cache entry is refreshed by {@link
   * CacheBuilder#refreshAfterWrite}, or through a call to {@link LoadingCache#refresh}.
   *
   * <p>This implementation synchronously delegates to {@link #load}. It is recommended that it be

      }
      return oldValue;
    }

    /**
     * Refreshes the value associated with {@code key}, unless another thread is already doing so.
     * Returns the newly refreshed value associated with {@code key} if it was refreshed inline, or
     * {@code null} if another thread is performing the refresh or if an error occurs during
     * refresh.
     */
    @CanIgnoreReturnValue
    @CheckForNull