What's Surefire Latest v2.22.1 default test runner?

I just realized unit tests can be executed without @RunWith, and also that from latest Surefire version, JUnit support is integrated (might be both events have a connection?), so I am trying to find what is the default surefire runner (JUnit version or runner class) when no RunWith is provided and no JUnit dependencies are placed in the classpath explictly by means of the POM