Use org.springframework.boot instead of ${project.groupId}
groupId in order to make it easier to use spring-boot-samples
modules as a starting point for new projects.
We get more control over the handling and in particular the registration
of the endpoint this way. It was practically impossible to disable the
AgentServlet bean when in a parent context of the management server
because of lifecyce issues - you don't know that the user wants a
separate management server until too late.
This approach also makes it possible to test with spring-test MVC
support.