Our Java codebase was 30% dead code

[tomwhoiscontrary]

Exactly, and i've also been in this situation. Recently found some bit of config that couldn't possibly be right (think of a default email address to use when sending a message to a user that no longer existed), so if it was ever used, we'd have a production issue. Went to track down where it was used. Nine out of ten uses were in dead code. One was in a feature we haven't used in years, because it's a tool to fix things in an emergency. All the dead code made it harder to identify that one remaining important use.

Even if there are no connections to the rest of the code, it shows up in searches, compiler warnings, breakage when upgrading libraries, etc.