Re: Help needed: maven-surefire-plugin is skipping/not finding tests
There is zero tests to run because you have globally specified a "groups"
but there are no tests annotated with such group in your project
Try to come over this issue by specifying empty groups in this child.
Let's go back to your three questions.
1. The pluginManagement should be in parent and children should not
specify/override plugin version, unless necessary.
2. You can use the latest version 2.22.0 but groups is old feature
available in 2.21.0 or 2.20.0 too and earlier.
3. Fix for groups is on your side, since you specify groups in parent POM
it means all children should undergo the same principle and all tests
should be annotated with one group at least. In your case when you still
have test which are not annotated with groups is to make the "groups"
config parameter empty. You can run the Maven in debug mode (mvn -X ...)
and you can see how the parameter is set in this plugin.