// different value
    assertFalse(segment.replace(key, hash, oldValue, newValue));
    assertEquals(1, segment.count);
    assertSame(newValue, segment.get(key, hash));

    // cleared
    segment.setWeakValueReferenceForTesting(entry, oldValueRef);
    oldValueRef.clear();
    assertFalse(segment.replace(key, hash, oldValue, newValue));
    assertEquals(0, segment.count);

    // different value
    assertFalse(segment.replace(key, hash, oldValue, newValue));
    assertEquals(1, segment.count);
    assertSame(newValue, segment.get(key, hash));

    // cleared
    segment.setWeakValueReferenceForTesting(entry, oldValueRef);
    oldValueRef.clear();
    assertFalse(segment.replace(key, hash, oldValue, newValue));
    assertEquals(0, segment.count);

     * block, and reference field assignment is atomic, this may save reacquiring the lock when
     * another thread or the worker task has cleared the count and set the state.
     *
     * <p>When {@link #executor} is a directExecutor(), the value written to
     * {@code workerRunningState} will be available synchronously, and behaviour will be
     * deterministic.

     * block, and reference field assignment is atomic, this may save reacquiring the lock when
     * another thread or the worker task has cleared the count and set the state.
     *
     * <p>When {@link #executor} is a directExecutor(), the value written to
     * {@code workerRunningState} will be available synchronously, and behaviour will be
     * deterministic.

        new TearDown() {

          @Override
          public void tearDown() throws Exception {
            synchronized (result.lock) {
              assertEquals(
                  "The test should have cleared the stack (say, by virtue of running runTearDown)",
                  0,
                  result.stack.size());
            }
          }
        });
    return result;
  }

     *   <li>If this field's value == null because it originally belonged to another thread and that
     *       thread cleared it, we still know that it's not associated with our thread
     *   <li>If this field's value == null because it was associated with our thread and was
     *       cleared, we know that we're not executing inline any more
     * </ul>
     *

    }

    @Override
    @CheckForNull
    protected EndpointPair<N> computeNext() {
      while (true) {
        /*
         * requireNonNull is safe because visitedNodes isn't cleared until this method calls
         * endOfData() (after which this method is never called again).
         */
        requireNonNull(visitedNodes);
        while (successorIterator.hasNext()) {

  // If data[i] == (byte) 0x80, the first cast will sign-extend it to 0xffffffffffffff80,
  // masking the remaining seven bytes.
  // To test this, we give an input where bit 7 is not cleared. For example:
  // (1) 00 01 02 03 04 05 06 07 80
  // (2) 00 01 02 03 04 05 06 07 81
  // (3) 00 01 02 03 04 05 06 07 ff (or anything in between)
  // A fault implementation will generate collisions for these inputs.

  // If data[i] == (byte) 0x80, the first cast will sign-extend it to 0xffffffffffffff80,
  // masking the remaining seven bytes.
  // To test this, we give an input where bit 7 is not cleared. For example:
  // (1) 00 01 02 03 04 05 06 07 80
  // (2) 00 01 02 03 04 05 06 07 81
  // (3) 00 01 02 03 04 05 06 07 ff (or anything in between)
  // A fault implementation will generate collisions for these inputs.

        new TearDown() {

          @Override
          public void tearDown() throws Exception {
            synchronized (result.lock) {
              assertEquals(
                  "The test should have cleared the stack (say, by virtue of running runTearDown)",
                  0,
                  result.stack.size());
            }
          }
        });
    return result;
  }