Don’t get hung up on strings, you can execute this attack with just comments. Look at the other examples in the paper.
The idea here is that you make part of the comment appear to be outside of it, and thus appear to be code that will be executed. You can reshuffle the text arbitrarily, so you can move text backwards to appear to be before the start of the comment, or forwards to appear to be after the end of the comment. If you really want to, you can treat the whole line as an anagram, and rearrange the individual letters into any order you like. This could enable really clever attacks where any use of an enum constant appears to be a use of a different one.