That definitely does happen with really poorly considered starting points, but in my experience it's also maybe a day's work to pull that apart and put it into Maven/Gradle (unless you've also got, like, some really terrifying ant stuff to go with it, and even then you can sometimes ask "is this even necessary?" and get with the chopping down).

IntelliJ even has tooling to get you started:

https://www.jetbrains.com/help/idea/convert-a-regular-projec...

The ant eclipse plugin does some lifting for you. Sometimes, it can be better this way than having 2 buildthings not in sync... But yeah ant all the way if everyone's happy with it...

I had to fix one such case 6 years ago where the build procedure was to build in IntelliJ.

It took a day or two to get kt over to Maven: basically create a Maven file, make sure everything were in the correct standard Java layout, then build and unzip the war file and compare it to the unzipped war file from the existing build process repeatedly while getting the last tweaks in place.

My team used to have stuff off that nature after we inherited the code base. Acquisition and movement of HQ meant a brand new team on a 15 year old B2B SaaS. Trying to move away from the combination of shell scripts, perl scripts, eclipse config, etc. Over to Gradle has been painful, but with it for onboarding new devs.