Java persistence with JPA and Hibernate, Part 2: Many-to-many relationships
https://www.javaworld.com/article/3387643/java-persistence-with-jpa-and-hibernate-part-2-many-to-many-relationships.html

Java 8 concurrency tutorial using Executors
https://winterbe.com/posts/2015/04/07/java8-concurrency-tutorial-thread-executor-examples/

Packed full of essential tips and tricks to modernise your code
https://blogs.oracle.com/javamagazine/java-modernization-streams-records-lambdas-sealedclasses

One of my favourite Java champions, this guy more than knows his stuff!
https://blog.sebastian-daschner.com/

Have Gitlab, Jira and Jenkins all play along nicely!
https://about.gitlab.com/blog/2018/07/30/gitlab-workflow-with-jira-jenkins/