stopwatch.start();
    assertSame(stopwatch, stopwatch.stop());
    assertFalse(stopwatch.isRunning());
  }

  public void testStop_new() {
    try {
      stopwatch.stop();
      fail();
    } catch (IllegalStateException expected) {
    }
    assertFalse(stopwatch.isRunning());
  }

  public void testStop_alreadyStopped() {
    stopwatch.start();
    stopwatch.stop();
    try {
      stopwatch.stop();

    stopwatch.start();
    assertSame(stopwatch, stopwatch.stop());
    assertFalse(stopwatch.isRunning());
  }

  public void testStop_new() {
    try {
      stopwatch.stop();
      fail();
    } catch (IllegalStateException expected) {
    }
    assertFalse(stopwatch.isRunning());
  }

  public void testStop_alreadyStopped() {
    stopwatch.start();
    stopwatch.stop();
    try {
      stopwatch.stop();

      - master
  pull_request:
    branches:
      - master

permissions:
  contents: read

jobs:
  test:
    permissions:
      actions: write  # for styfle/cancel-workflow-action to cancel/stop running workflows
      contents: read  # for actions/checkout to fetch code
    name: "${{ matrix.root-pom }} on JDK ${{ matrix.java }} on ${{ matrix.os }}"
    strategy:
      matrix:
        os: [ ubuntu-latest ]

 *
 * <p>{@code RuntimeException}s thrown by tasks are simply logged and the executor keeps trucking.
 * If an {@code Error} is thrown, the error will propagate and execution will stop until it is
 * restarted by a call to {@link #execute}.
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault
final class SequentialExecutor implements Executor {

   * <p>When the underlying delegate throws an exception then this memoizing supplier will keep
   * delegating calls until it returns valid data.
   *
   * @param duration the length of time after a value is created that it should stop being returned
   *     by subsequent {@code get()} calls
   * @param unit the unit that {@code duration} is expressed in
   * @throws IllegalArgumentException if {@code duration} is not positive
   * @since 2.0
   */

 * {@link #runOneIteration} that will be executed periodically as specified by its {@link
 * Scheduler}. When this service is asked to stop via {@link #stopAsync} it will cancel the periodic
 * task (but not interrupt it) and wait for it to stop before running the {@link #shutDown} method.
 *
 * <p>Subclasses are guaranteed that the life cycle methods ({@link #runOneIteration}, {@link

            <!-- Even after we stop using JSR305 annotations in our own code, we'll want this link so that NullPointerTester's docs can link to @CheckForNull and friends... at least once we start using this config for guava-testlib. -->
            <offlineLink>

   * the {@code shutdownNow} method. First, "best-effort" with regards to canceling running tasks is
   * implemented as "no-effort". No interrupts or other attempts are made to stop threads executing
   * tasks. Second, the returned list will always be empty, as any submitted task is considered to
   * have started execution. This applies also to tasks given to {@code invokeAll} or {@code

    /**
     * The elements to be returned by future calls to {@code next()}, with the first at the top of
     * the stack.
     */
    final Stack<E> nextElements = new Stack<>();

    /**
     * The elements to be returned by future calls to {@code previous()}, with the first at the top
     * of the stack.
     */
    final Stack<E> previousElements = new Stack<>();

    /**

        b = entries.get(1);
        c = entries.get(2);
      }
    }
  }

  /** Resets the contents of navigableMap to have entries a, c, for the navigation tests. */
  @SuppressWarnings("unchecked") // Needed to stop Eclipse whining
  private void resetWithHole() {
    Entry<K, V>[] entries = (Entry<K, V>[]) new Entry<?, ?>[] {a, c};
    super.resetMap(entries);
    navigableMap = (NavigableMap<K, V>) getMap();
  }