We've been accumulating quite a few warnings during the prototype phase of Search 6. We should definitely get rid of them.

And maybe add some checks to make the CI build fail on un-suppressed warnings, to stop warnings from accumulating again. Let's ignore the legacy code, though: we won't waste our time removing warnings there.

Also it would be great to find some way to make the warnings more prominent in IDEA, because currently I only see them when I look at the exact line where the warning appears... There's no general view like in Eclipse :/