* to calling it exactly once.
   *
   * @since 10.0 (present in 1.0 as {@code run})
   */
  public void execute() {
    // Lock while we update our state so the add method above will finish adding any listeners
    // before we start to run them.
    RunnableExecutorPair list;
    synchronized (this) {
      if (executed) {
        return;
      }

    String message = "Waited " + timeout + " " + unit.toString().toLowerCase(Locale.ROOT);
    // Only report scheduling delay if larger than our spin threshold - otherwise it's just noise
    if (remainingNanos + SPIN_THRESHOLD_NANOS < 0) {
      // We over-waited for our timeout.
      message += " (plus ";
      long overWaitNanos = -remainingNanos;
      long overWaitUnits = unit.convert(overWaitNanos, TimeUnit.NANOSECONDS);

                return null;
            }
        }

        //
        // Here we just need to know that a version is fine to use but this validation we can do in our workspace
        // resolver.
        //

        /*
         * if ( version == null || !version.equals( parent.getVersion() ) ) { return null; }
         */

   *
   * @since 2.0
   */
  public abstract static class SetView<E extends @Nullable Object> extends AbstractSet<E> {
    private SetView() {} // no subclasses but our own

    /**
     * Returns an immutable copy of the current contents of this set view. Does not support null
     * elements.
     *

 * <p>If you are using Java 8+, this class is now obsolete. Most of its functionality is now
 * provided by {@link java.util.stream.Stream Stream} and by {@link Comparator} itself, and the rest
 * can now be found as static methods in our new {@link Comparators} class. See each method below
 * for further instructions. Whenever possible, you should change any references of type {@code

      }

      @Override
      public I next() {
        if (!hasNext()) {
          throw new NoSuchElementException();
        }
        /*
         * requireNonNull is safe because our callers always pass non-null arguments. Each element
         * of the array becomes null only when we iterate past it and then clear it.
         */
        I result = requireNonNull(elements[index]);

      /*
       * requireNonNull is safe because propertyNames contains only non-null elements.
       *
       * Accordingly, we have it annotated as returning `Enumeration<? extends Object>` in our
       * prototype checker's JDK. However, the checker still sees the return type as plain
       * `Enumeration<?>`, probably because of one of the following two bugs (and maybe those two

     * Wrapper<Number>, Wrapper<Integer>, Wrapper<@Nullable Integer>, etc. If we used just
     * Equivalence<? super T> below, no type could satisfy both that bound and T's own
     * bound. With this type, they have some overlap: in our example, Equivalence<Number>
     * and Equivalence<Object>.
     */
    private final Equivalence<? super @NonNull T> equivalence;

    @ParametricNullness private final T reference;

     * use `get(key) ?: defaultValue` instead of this method, anyway.
     */
    V result = get(key);
    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
    if (result != null) {
      return result;
    } else {
      return defaultValue;
    }
  }

     * the second version is the newer.
     */
    private static int compareModelVersions(String first, String second) {
        // we use a dedicated comparator because we control our model version scheme.
        String[] firstSegments = first.split("\\.");
        String[] secondSegments = second.split("\\.");
        for (int i = 0; i < Math.max(firstSegments.length, secondSegments.length); i++) {