assertFalse(collection.spliterator().hasCharacteristics(Spliterator.NONNULL));
    }
  }

  @CollectionFeature.Require(SUPPORTS_ADD)
  public void testSpliteratorNotImmutable_CollectionAllowsAdd() {
    // If add is supported, verify that IMMUTABLE is not reported.
    synchronized (collection) { // for Collections.synchronized
      assertFalse(collection.spliterator().hasCharacteristics(Spliterator.IMMUTABLE));
    }
  }