In a thread from 2015 Otis suggests this could be added to v5. Is it in v5?

Not yet. I'll make sure the dev team, gets your request.

Not yet, but it's on the list to add in a future v5 version. Other things were considered more important for the previous v5 versions however hence it wasn't implemented.

Is it in the current version?

Hi JayBee,

I didn't found this in the changelog or recent documentation. What are you trying to do exactly? Maybe we can help you in another way.

It's not yet added, we didn't give it a high priority (but still a workitem), as they're merely edge cases. If you want it today, it's best to create your own FieldLikePredicate class (e.g. by copying the code from the runtime lib source) and add the {escape ' escape-character '} yourself. If you need help with that, let us know.