@Chris Cranford thank you for your clarification. I have filed the issue back to the spring data jpa team, where i opened it up originally.
For me, the spring boot auto configuration stuff is just great, because i don´t have to care about all the different configurations.
Moreover with spring data jpa i don´t have to care about all the ORM specific "under the hood" switches and types.
But that´s another story

Thank you for your quick help.

Kind regards
Thomas