public void testSubmit() throws Exception {
    /*
     * Mostly just tests that TrustedListenableFutureTask are created and run; tests for
     * TrustedListenableFutureTask should ensure that listeners are called correctly.
     */

    TestListeningExecutorService e = new TestListeningExecutorService();

    TestRunnable runnable = new TestRunnable();
    ListenableFuture<?> runnableFuture = e.submit(runnable);

FIELD com.google.common.collect.TreeTraverser.PreOrderIterator.stack
FIELD com.google.common.util.concurrent.AbstractFuture.Listener.executor com.google.common.util.concurrent.MoreExecutors.rejectionPropagatingExecutor.$
FIELD com.google.common.util.concurrent.AbstractService.listeners
# NonReentrantExecutor is not exposed to this field

    for (int k = 0; k < 50; k++) {
      // For each listener we add a task that submits it to the executor directly for the blocking
      // get use case and another task that adds it as a listener to the future to exercise both
      // racing addListener calls and addListener calls completing after the future completes.
      Runnable listener = k % 2 == 0 ? collectResultsRunnable : collectResultsTimedGetRunnable;

      RunnableExecutorPair list;
      synchronized (this) {
        if (executed) {
          return;
        }
        executed = true;
        list = runnables;
        runnables = null; // allow GC to free listeners even if this stays around for a while.
      }
      while (list != null) {
        executeListener(list.runnable, list.executor);
        list = list.next;
      }
    }

        AbstractFutureState<?> future, @Nullable Listener expect, Listener update) {
      return UNSAFE.compareAndSwapObject(future, LISTENERS_OFFSET, expect, update);
    }

    @Override
    @Nullable Listener gasListeners(AbstractFutureState<?> future, Listener update) {
      while (true) {
        Listener listener = future.listenersField;
        if (update == listener) {
          return listener;
        }

### Events with Retries and Follow-Ups

OkHttp is resilient and can automatically recover from some connectivity failures. In this case, the `connectFailed()` event is not terminal and not followed by `callFailed()`. Event listeners will receive multiple events of the same type when retries are attempted.

    }

    @Override
    boolean casListeners(
        AbstractFutureState<?> future, @Nullable Listener expect, Listener update) {
      return listenersUpdater.compareAndSet(future, expect, update);
    }

    @Override
    @Nullable Listener gasListeners(AbstractFutureState<?> future, Listener update) {
      return (Listener) listenersUpdater.getAndSet(future, update);
    }

    @Override

import java.util.ArrayList;
import java.util.List;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Validate that {@link EventBus} behaves carefully when listeners publish their own events.
 *
 * @author Jesse Wilson
 */
@NullUnmarked
public class ReentrantEventsTest extends TestCase {

  static final String FIRST = "one";
  static final Double SECOND = 2.0d;

     */
    @Override
    public void addListener(Runnable listener, Executor exec) {
      executionList.add(listener, exec);
    }

    /**
     * Subclasses should invoke this method to set the result of the computation to {@code value}.
     * This will set the state of the future to {@link OldAbstractFuture.Sync#COMPLETED} and invoke
     * the listeners if the state was successfully changed.
     *

       * lets all futures share the same listener.
       *
       * We store `localFuturesOrNull` inside the listener because `this.futures` might be nulled
       * out by the time the listener runs for the final future -- at which point we need to check
       * all inputs for exceptions *if* we're collecting values. If we're not, then the listener