});
    }
  }

  private void invokeOnExecutionThreadForTest(Runnable runnable) {
    executionThread = new Thread(runnable);
    executionThread.setUncaughtExceptionHandler(
        (thread, throwable) -> thrownByExecutionThread = throwable);
    executionThread.start();
  }

  private static void throwIfSet(Throwable t) throws Throwable {
    if (t != null) {

          });
    }
  }

  private void invokeOnExecutionThreadForTest(Runnable runnable) {
    executionThread = new Thread(runnable);
    executionThread.setUncaughtExceptionHandler(
        (thread, throwable) -> thrownByExecutionThread = throwable);
    executionThread.start();
  }

  private static void throwIfSet(Throwable t) throws Throwable {
    if (t != null) {

    List<Thread> threads = new ArrayList<>(numThreads);
    List<Throwable> exceptions = new ArrayList<>(numThreads);
    for (int i = 0; i < numThreads; i++) {
      Thread thread = new Thread(task);
      thread.setUncaughtExceptionHandler((t, throwable) -> exceptions.add(throwable));
      threads.add(thread);
    }
    for (Thread t : threads) {
      t.start();
    }
    for (Thread t : threads) {