return ImmutableList.copyOf(elements);
  }

  public void testCopyOf_concurrentlyMutatedList() {
    runConcurrentlyMutatedTest(WrapWithIterable.NO_WRAP);
  }

  public void testCopyOf_concurrentlyMutatedIterable() {
    runConcurrentlyMutatedTest(WrapWithIterable.WRAP);
  }

  /** An operation to perform on a list. */
  interface ListFrobber {
    void perform(List<Integer> list);
  }