To give a precise answer, you'd need to provide the relevant source code (which I would have told you in a comment, if Stackoverflow would allow me to write a comment with my current level of reputation...).

From what I can see from the stacktrace, you have a class Controller that has a reference to a Service which has a reference to Repository, which seams to be dealing with Persons and is complaining that br.com.example.spring_boot_and_kotlin.model.Person is not a managed type.

I guess it is missing an @Entity annotation or something like that, but as said, a precise answer would require the relevant source code.