Javassist is not dead yet but it is just minimally maintained and does not seem to have a great future. bytecode level support for latest released jdk is usually added quite late but source level support is never added. At source level it is still Java 1.4 compatible. We need a high level java bytecode library to replace it, and also play well in the Quarkus ecosystem. ByteBuddy and Gizmo seem to be the right candidates.