Instead, JUnit provides a gentle migration path via a JUnit Vintage test engine which allows existing tests based on JUnit 3 and JUnit 4 to be executed using the JUnit Platform infrastructure. Since all classes and annotations specific to JUnit Jupiter reside under a new base package, having both JUnit 4 and JUnit Jupiter in the classpath does not lead to any conflicts. It is therefore safe to maintain existing JUnit 4 tests alongside JUnit Jupiter tests. Furthermore, since the JUnit team will continue to provide maintenance and bug fix releases for the JUnit 4.x baseline, developers have plenty of time to migrate to JUnit Jupiter on their own schedule.