JUnit 5 vintage is a way to run JUnit 4 code with the JUnit 5 runner.
This is the first step in the migration from JUnit 4 to JUnit 5 of PLANNER-1003.

Requirements/pointers:

• Go to youtube and look at a good "devoxx junit 5" presentation from november 2017 or later.
• First build all of KIE and run all tests. This will take hours.
  • clone https://github.com/kiegroup/droolsjbpm-build-bootstrap
  • script/git-clone-others.sh
  • script/mvn-all.sh mvn clean install // don't do -DskipTests!
• Write down how long it took to run all tests (ask jhrcek how to get that info easily - it's not the build time as that includes maven snapshot downloads)
  • if you do end up using the build time, build twice and measure the time when doing a "no snapshot update" build.
• in kie-parent, change the junit dependencies and the maven surefire plugin and maven failsafe plugin so that it uses the JUnit 5 runner and so that it adds the junit vintage dependency instead of the junit:junit:4 dependencies.
• Go through all projects and look for specific usages of <artifactId>junit< or assembly references of "junit:junit"
• Build all of KIE and run all tests. It should all work.
• Report the difference in test time here (or in "no snapshot update" build time)
• check if the coverage is the same.