* the life cycle methods.
 *
 * <h3>Usage Example</h3>
 *
 * <p>Here is a sketch of a service which crawls a website and uses the scheduling capabilities to
 * rate limit itself.
 *
 * <pre>{@code
 * class CrawlingService extends AbstractScheduledService {
 *   private Set<Uri> visited;
 *   private Queue<Uri> toCrawl;
 *   protected void startUp() throws Exception {

         * higher than the current batchLevel so we will now encode
         * that chained message. Before doing so we must increment
         * the batchLevel of the andx message in case it itself is an
         * andx message and needs to perform the same check as above.
         */

        this.andx.batchLevel = this.batchLevel + 1;

        dst[ start + ANDX_COMMAND_OFFSET ] = this.andxCommand;

   * to reference the FinalizableReferenceQueue class then its ClassLoader cannot be
   * garbage-collected, even if there are no more instances of FinalizableReferenceQueue itself.
   * The code in FinalizableReferenceQueue goes to considerable trouble to ensure that there are
   * no such references and the tests here check that that trouble has not been in vain.
   *

    private boolean parallel;

    /**
     * Plugin context keyed by project ({@link MavenProject#getId()}) and by plugin lookup key
     * ({@link PluginDescriptor#getPluginLookupKey()}). Plugin contexts itself are mappings of {@link String} keys to
     * {@link Object} values.
     */
    @SuppressWarnings("checkstyle:linelength")
    private final ConcurrentMap<String, ConcurrentMap<String, ConcurrentMap<String, Object>>>

 *
 * <ol>
 *   <li>Expose a public method, known as the <i>event subscriber</i>, which accepts a single
 *       argument of the type of event desired;
 *   <li>Mark it with a {@link Subscribe} annotation;
 *   <li>Pass itself to an EventBus instance's {@link #register(Object)} method.
 * </ol>
 *
 * <h2>Posting Events</h2>
 *
 * <p>To post an event, simply provide the event object to the {@link #post(Object)} method. The

   * @return {@code string} itself if it is non-null; {@code ""} if it is null
   */
  public static String nullToEmpty(@CheckForNull String string) {
    return Platform.nullToEmpty(string);
  }

  /**
   * Returns the given string if it is nonempty; {@code null} otherwise.
   *
   * @param string the string to test and possibly return
   * @return {@code string} itself if it is nonempty; {@code null} if it is empty or null

  private static final String ERROR_ADDED_PARALLEL_EDGE =
      "Should not be allowed to add a parallel edge.";
  private static final String ERROR_ADDED_SELF_LOOP =
      "Should not be allowed to add a self-loop edge.";
  static final String ERROR_SELF_LOOP = "self-loops are not allowed";

  @Test
  public void transitiveClosure_directedGraph() {

			"Time elapsed (in nano seconds) since last self healing activity. This is set to -1 until initial self heal activity",
			nil, nil),
		prometheus.GaugeValue,
		float64(dur),
	)
	for k, v := range bgSeq.getScannedItemsMap() {
		ch <- prometheus.MustNewConstMetric(
			prometheus.NewDesc(
				prometheus.BuildFQName(healMetricsNamespace, "objects", "scanned"),
				"Objects scanned in current self healing run",
				[]string{"type"}, nil),

  private static final String ERROR_ADDED_PARALLEL_EDGE =
      "Should not be allowed to add a parallel edge.";
  private static final String ERROR_ADDED_SELF_LOOP =
      "Should not be allowed to add a self-loop edge.";
  static final String ERROR_SELF_LOOP = "self-loops are not allowed";

  @Test
  public void transitiveClosure_directedGraph() {

          if (nanos == 0L) return

          // Yield until notified, interrupted, or the duration elapses.
          val waitUntil = nanoTime + nanos
          val self = currentTask
          waitingCoordinatorTask = self
          waitingCoordinatorNotified = false
          waitingCoordinatorInterrupted = false
          yieldUntil {