task.getDestinationDirectory().convention(layout.getBuildDirectory().dir("tmp/" + task.getName()));
        });

        TaskProvider<Sync> userguideFlattenSources = tasks.register("stageUserguideSource", Sync.class, task -> {
            task.setDuplicatesStrategy(DuplicatesStrategy.FAIL);

            // TODO: This doesn't allow adoc files to be generated?

   * as implementation details.
   *
   * <p>Since the bimap is immutable, ImmutableBiMap doesn't require special logic for keeping the
   * bimap and its inverse in sync during serialization, the way AbstractBiMap does.
   */
  @J2ktIncompatible // serialization
  private static class SerializedForm<K, V> extends ImmutableMap.SerializedForm<K, V> {

      implements CycleDetectingLock {

    // These ReadLock/WriteLock implementations shadow those in the
    // ReentrantReadWriteLock superclass. They are simply wrappers around the
    // internal Sync object, so this is safe since the shadowed locks are never
    // exposed or used.
    private final CycleDetectingReentrantReadLock readLock;
    private final CycleDetectingReentrantWriteLock writeLock;