2019 was a very busy year in terms of conferences. Our team could leave for whole weeks on business trips. As you know, the conference is perfect time to share knowledge. In addition to giving talks and telling many interesting things at our booth, we also learned a lot from communicating with conference participants and speakers. So at the Joker 2019 conference in fall, a talk from Dalia Abo Sheasha «Migrating beyond Java 8» inspired us to implement a new diagnostic rule that allows us to detect incompatibilities in the Java SE API between different versions of Java. This is what we will talk about.