*   <li>The state of the RateLimiter (storedPermits) is a vertical line in this figure.
   *   <li>When the RateLimiter is not used, this goes right (up to maxPermits)
   *   <li>When the RateLimiter is used, this goes left (down to zero), since if we have
   *       storedPermits, we serve from those first
   *   <li>When _unused_, we go right at a constant rate! The rate at which we move to the right is

   * a {@link MoveDesc}. The first one is the element that was previously at the end of the heap and
   * is now at some position before {@code index}. The second element is the one that was swapped
   * down to replace the element at {@code index}. This fact is used by iterator.remove so as to
   * visit elements during a traversal once and only once.
   */
  @VisibleForTesting
  @CanIgnoreReturnValue
  @CheckForNull

        users indicates that they really appreciate Guava's high power-to-weight ratio. It's
        important to us to keep Guava as easy to use and understand as we can. That means boiling
        features down to compact but powerful abstractions, and controlling feature bloat carefully.


        Guava's main yardstick for evaluating proposed features can be summed up as [utility times

          instance,
          ArbitraryInstances.get(mutableClass));
    }
  }

  private enum EmptyEnum {}

  private enum Direction {
    UP,
    DOWN
  }

  public interface SomeInterface {}

  public abstract static class SomeAbstractClass {
    public static final SomeAbstractClass INSTANCE = new SomeAbstractClass() {};

    return isRunning ? ticker.read() - startTick + elapsedNanos : elapsedNanos;
  }

  /**
   * Returns the current elapsed time shown on this stopwatch, expressed in the desired time unit,
   * with any fraction rounded down.
   *
   * <p><b>Note:</b> the overhead of measurement can be more than a microsecond, so it is generally
   * not useful to specify {@link TimeUnit#NANOSECONDS} precision here.
   *

    String string = Strings.repeat("0123456789", 100);
    StringBuilder b = new StringBuilder();
    // the main assertion of this test is here... the copy will fail if the buffer size goes down
    // each time it is not filled completely
    long copied = CharStreams.copy(newNonBufferFillingReader(new StringReader(string)), b);
    assertEquals(string, b.toString());
    assertEquals(string.length(), copied);

    String string = Strings.repeat("0123456789", 100);
    StringBuilder b = new StringBuilder();
    // the main assertion of this test is here... the copy will fail if the buffer size goes down
    // each time it is not filled completely
    long copied = CharStreams.copy(newNonBufferFillingReader(new StringReader(string)), b);
    assertEquals(string, b.toString());
    assertEquals(string.length(), copied);

    for (LogRecord record : logHandler.getStoredLogRecords()) {
      assertThat(logFormatter.format(record)).doesNotContain("NoOpService");
    }
  }

  /**
   * Tests that a ServiceManager can be fully shut down if one of its failure listeners is slow or
   * even permanently blocked.
   */
  public void testListenerDeadlock() throws InterruptedException {
    final CountDownLatch failEnter = new CountDownLatch(1);

  protected void tearDown() throws Exception {

    // Make sure we have no waiting threads.
    latch.countDown();
  }

  /** Constructs a listenable future with a value available after the latch has counted down. */
  protected abstract <V> ListenableFuture<V> createListenableFuture(
      V value, @Nullable Exception except, CountDownLatch waitOn);

  /** Tests that the {@link Future#get()} method blocks until a value is available. */

       * finalizable references could be enqueued subsequently (at which point the class loader
       * would be resurrected by virtue of us having a strong reference to it), we should pretty
       * much just shut down and make sure we don't keep it alive any longer than necessary.
       */
      return null;
    }
    try {
      return finalizableReferenceClass.getMethod("finalizeReferent");