If the build version of the instance is present in the metadata it's now
also considered and the version is now a attribute on the instance
itself. So when using non-boot application they can provide it via the
registration metadata.

Don't output metadata in Registration.toString()

It's indended by the Jackson developers to extend StdDeserializer and
not the JsonDeserializer

It turns out that imho when talking about application groups (identified
by name) and application instances it's just logical to speak of
instances and applications. So the Application class get's renamed to
Instance. So an Application is now a set of Instances with the same name

The actuator endpoints are detected by either querying the index
endpoint for spring boot 2.x applications or by probing a configurable
list of endpoints using a OPTIONS request.