After JUnit 5 was released, a lot of developers just added this awesome new library to their projects, because unlike other versions, in this new version, it is not necessary to migrate from JUnit 4 to 5, you just need to include the new library in your project, and with all the engine of JUnit 5 you can do your new tests using JUnit 5, and the older one with JUnit 4 or 3, will keep running without problem.
But what can happen in a big project, a project that was built 10 years ago with two versions of JUnit running in parallel?