This fails:

    public int test(Object o)
    {
        int[] arr = {1, 2};

        return switch (o) {
            case (String s) when (arr[0] == 1) -> 0;
            default -> 1;
        };
    }

with

    ParenthesizedCombo.java:36: error: -> expected
                case (String s) when (arr[0] == 1) -> 0;

but not when e.g.,

    case (String s) when (s.isEmpty()) -> 0;