Preserve empty contents tag?

Hi guys, first of all, thanks for a great job in the library :tada:

I wanted to know if there's a way to preserve the changes done in #300 and in #307 are somehow configurable?

To give you some idea, we made a **HUGE** jump from version `0.11.3.0` to `1.4.7.1` (yes the app is really old and has a bunch of tech debt) and with the issue and PR I mentioned, it broke a lot of internal stuff for us, so I was wondering if there's a workaround to preserve `contents: []` for single constructors?

We have tons for ADTs like the following:

``` haskell
data Foo = Foo Text | Bar;
```

Thanks in advance for the help with this!