scala 2.12 (https://bugs.debian.org/1149686) replaces scala 2.11 in unstable. Its scala-library Breaks the 2.11 build of plm, and plm needs source changes to build with 2.12. The fix is in https://salsa.debian.org/java-team/plm/-/merge_requests/4. It also fixes https://bugs.debian.org/1139926 and https://bugs.debian.org/1139932. Upload it after scala 2.12 reaches unstable.