* to any {@code Runnable} passed to the default implementation of {@link #wrapTask(Runnable)}.
   */
  protected abstract <T extends @Nullable Object> Callable<T> wrapTask(Callable<T> callable);

  /**
   * Wraps a {@code Runnable} for submission to the underlying executor. The default implementation
   * delegates to {@link #wrapTask(Callable)}.
   */
  protected Runnable wrapTask(Runnable command) {

                  + runnable
                  + " with executor "
                  + executor,
              e);
    }
  }

  private static final class RunnableExecutorPair {
    final Runnable runnable;
    final Executor executor;
    @Nullable RunnableExecutorPair next;

    RunnableExecutorPair(

                  + runnable
                  + " with executor "
                  + executor,
              e);
    }
  }

  private static final class RunnableExecutorPair {
    final Runnable runnable;
    final Executor executor;
    @Nullable RunnableExecutorPair next;

    RunnableExecutorPair(

    @Override
    public void execute(Runnable runnable) {
      assertThat(runnable).isInstanceOf(TrustedListenableFutureTask.class);
      runnable.run();
    }

    @Override
    public void shutdown() {}

    @Override
    public List<Runnable> shutdownNow() {
      return ImmutableList.of();
    }

    @Override
    public boolean isShutdown() {
      return false;
    }

    @Override

    @Override
    public void execute(Runnable runnable) {
      assertThat(runnable).isInstanceOf(TrustedListenableFutureTask.class);
      runnable.run();
    }

    @Override
    public void shutdown() {}

    @Override
    public List<Runnable> shutdownNow() {
      return ImmutableList.of();
    }

    @Override
    public boolean isShutdown() {
      return false;
    }

    @Override

  }

  @JvmStatic
  fun threadFactory(name: String): ThreadFactory =
    object : ThreadFactory {
      private var nextId = 1

      override fun newThread(runnable: Runnable): Thread = Thread(runnable, "$name-${nextId++}")
    }
}

fun getEnv(name: String) = System.getenv(name)

val SYSTEM_FILE_SYSTEM = FileSystem.SYSTEM

            }
            runCalled.getAndIncrement();
          }
        },
        directExecutor());
    Runnable execute =
        new Runnable() {
          @Override
          public void run() {
            list.execute();
          }
        };
    Thread thread1 = new Thread(execute);
    Thread thread2 = new Thread(execute);
    thread1.start();
    thread2.start();

            }
            runCalled.getAndIncrement();
          }
        },
        directExecutor());
    Runnable execute =
        new Runnable() {
          @Override
          public void run() {
            list.execute();
          }
        };
    Thread thread1 = new Thread(execute);
    Thread thread2 = new Thread(execute);
    thread1.start();
    thread2.start();

  private val loggingUncaughtExceptionHandler =
    UncaughtExceptionHandler { _, throwable ->
      log.put("uncaught exception: $throwable")
    }

  private val threadFactory =
    ThreadFactory { runnable ->
      Thread(runnable, "TaskRunnerRealBackendTest").apply {
        isDaemon = true
        uncaughtExceptionHandler = loggingUncaughtExceptionHandler
      }
    }

  private val backend = TaskRunner.RealBackend(threadFactory)

      Runnable runnable, @ParametricNullness V result) {
    return new ListenableFutureTask<>(runnable, result);
  }

  ListenableFutureTask(Callable<V> callable) {
    super(callable);
  }

  ListenableFutureTask(Runnable runnable, @ParametricNullness V result) {
    super(runnable, result);
  }

  @Override
  public void addListener(Runnable listener, Executor exec) {