}
                }),
            executor);

    // Pause in step 2.
    step2Waiter.awaitStarted();

    // Everything should still be open.
    assertStillOpen(closeable1, closeable2, closeable3, closeable4);

    // Cancel step 3, resume step 2, and pause in step 4.
    assertWithMessage("step3.cancel()").that(step3.cancel(false)).isTrue();
    step2Waiter.awaitReturned();

    // except TypeVariable.
    return of(new TypeResolver().resolveType(runtimeType));
  }

  /**
   * Ensures that this type token doesn't contain type variables, which can cause unchecked type
   * errors for callers like {@link TypeToInstanceMap}.
   */
  @CanIgnoreReturnValue
  final TypeToken<T> rejectTypeVariables() {
    new TypeVisitor() {
      @Override