while (true) {
        Listener listener = future.listeners;
        if (update == listener) {
          return listener;
        }
        if (casListeners(future, listener, update)) {
          return listener;
        }
      }
    }

    /** Performs a GAS operation on the {@link #waiters} field. */
    @Override
    Waiter gasWaiters(AbstractFuture<?> future, Waiter update) {
      while (true) {

    if (!isDone()) {
      Listener oldHead = listeners;
      if (oldHead != Listener.TOMBSTONE) {
        Listener newNode = new Listener(listener, executor);
        do {
          newNode.next = oldHead;
          if (ATOMIC_HELPER.casListeners(this, oldHead, newNode)) {
            return;
          }
          oldHead = listeners; // re-read
        } while (oldHead != Listener.TOMBSTONE);

        ModelBuildingListener listener = getModelBuildingListener(request);

        if (listener != null) {
            AtomicReference<Model> m = new AtomicReference<>(model);

            ModelBuildingEvent event = new DefaultModelBuildingEvent(model, m::set, request, problems);

            catapult.accept(listener, event);

            return m.get();
        }

                            .source(modelSource)
                            .projectBuild(true)
                            .locationTracking(true)
                            .listener(listener)
                            .build();

                    if (pomFile != null) {
                        project.setRootDirectory(rootLocator.findRoot(pomFile.getParent()));
                    }

  // operation in the constructor.
  //
  // 1. In the listener that performs the callback. In this case it is fine since inputFuture is
  //    assigned prior to calling addListener, and addListener happens-before any invocation of the
  //    listener. Notably, this means that 'volatile' is unnecessary to make 'inputFuture' visible
  //    to the listener.
  //

            ModelBuildingEventCatapult catapult) {
        ModelBuildingListener listener = request.getModelBuildingListener();

        if (listener != null) {
            ModelBuildingEvent event = new DefaultModelBuildingEvent(model, request, problems);

            catapult.fire(listener, event);
        }
    }

  // operation in the constructor.
  //
  // 1. In the listener that performs the callback. In this case it is fine since inputFuture is
  //    assigned prior to calling addListener, and addListener happens-before any invocation of the
  //    listener. Notably, this means that 'volatile' is unnecessary to make 'inputFuture' visible
  //    to the listener.
  //