The java part `plc4j` was for a long time the "primary" language of plc4x. But with other parts gaining more traction (plc4go, plc4net and plc4py as a latest addition) it was about time to not call it the favorite child anymore. With the recent change in the develop branch you now need to enable plc4j with `-Pwith-java` if you working on the java part of plc4x. All documentation and build script have been updated. Also at this point a friendly reminder: If you change something on the mspec make sure it works on all languages (you can check the github language related build jobs for that). If there is for some reason the need to skip the others there is the possibility to version the mspec and upgrade the other languages later.
Best Regards, The plc4x Team
