Agent Skills: java

Java language and JVM engineering standards — records and sealed-type modelling, JSpecify null-safety with NullAway as a build error, immutability, virtual threads and modern concurrency, Error Prone/ArchUnit/PIT build gates, JUnit 6 testing doctrine, and boundary security. Load whenever writing, refactoring, or reviewing Java: any .java file, pom.xml/build.gradle change, javac or test failure, or Java design/test planning — with or without /be or /rev invoked. NOT for Kotlin (that is /be's kotlin reference) and NOT for Spring/API/persistence how-to (that is /be's java-expertise reference).