}
      };

  /**
   * A Throwable used to record a stack trace that illustrates an example of a specific lock
   * acquisition ordering. The top of the stack trace is truncated such that it starts with the
   * acquisition of the lock in question, e.g.
   *
   * <pre>
   * com...ExampleStackTrace: LockB -&gt; LockC
   *   at com...CycleDetectingReentrantLock.lock(CycleDetectingLockFactory.java:443)

        totalCount = laterCount = currentEntry.getCount();
      }
      laterCount--;
      canRemove = true;
      /*
       * requireNonNull is safe because laterCount starts at 0, forcing us to initialize
       * currentEntry above. After that, we never clear it.
       */
      return requireNonNull(currentEntry).getElement();
    }

    @Override

    return new Stopwatch(ticker);
  }

  /**
   * Creates (and starts) a new stopwatch using {@link System#nanoTime} as its time source.
   *
   * @since 15.0
   */
  public static Stopwatch createStarted() {
    return new Stopwatch().start();
  }

  /**
   * Creates (and starts) a new stopwatch, using the specified time source.
   *
   * @since 15.0
   */

   * service changes state. The listener will not have previous state changes replayed, so it is
   * suggested that listeners are added before the service starts.
   *
   * <p>{@code addListener} guarantees execution ordering across calls to a given listener but not
   * across calls to multiple listeners. Specifically, a given listener will have its callbacks

        || validSurrogatePairAt(b, b.length() - s - 1)) {
      s--;
    }
    return a.subSequence(a.length() - s, a.length()).toString();
  }

  /**
   * True when a valid surrogate pair starts at the given {@code index} in the given {@code string}.
   * Out-of-range indexes return false.
   */
  @VisibleForTesting
  static boolean validSurrogatePairAt(CharSequence string, int index) {
    return index >= 0

 *       code, or even to discover <i>any</i> two distinct inputs that yield the same result. These
 *       are called <i>cryptographic hash functions</i>. But, whenever it is learned that either of
 *       these feats has become computationally feasible, the function is deemed "broken" and should
 *       no longer be used for secure purposes. (This is the likely eventual fate of <i>all</i>
 *       cryptographic hashes.)

    assertEquals(refreshKey + suffix, map.get(refreshKey));
  }

  public void testInvalidateDuringLoading() throws InterruptedException, ExecutionException {
    // computation starts; invalidate() is called on the key being computed, computation finishes
    final CountDownLatch computationStarted = new CountDownLatch(2);
    final CountDownLatch letGetFinishSignal = new CountDownLatch(1);

        }
      };

  private static void checkResult(Joiner joiner, Iterable<Integer> parts, String expected) {
    assertEquals(expected, joiner.join(parts));
    assertEquals(expected, joiner.join(parts.iterator()));

    StringBuilder sb1FromIterable = new StringBuilder().append('x');
    joiner.appendTo(sb1FromIterable, parts);
    assertEquals("x" + expected, sb1FromIterable.toString());

            "+1.+2.+3.4",
            "1.2.3.4e0",
            "6:5:4:3:2:1:0", // too few parts
            "::7:6:5:4:3:2:1:0", // too many parts
            "7:6:5:4:3:2:1:0::", // too many parts
            "9:8:7:6:5:4:3::2:1", // too many parts
            "0:1:2:3::4:5:6:7", // :: must remove at least one 0.
            "3ffe:0:0:0:0:0:0:0:1", // too many parts (9 instead of 8)
            "3ffe::10000", // hextet exceeds 16 bits

          sb.append(DELIMITER_STRING);
        }
        sb.append(comp);
        append = true;
      }
      dummy ^= sb.toString().length();
    }
    return dummy;
  }

  /**
   * Starts with an empty delimiter and changes to the desired value at the end of the iteration.
   */
  @Benchmark
  int assignDelimiter(int reps) {
    int dummy = 0;
    for (int i = 0; i < reps; i++) {