[okeuro49]

> You can use the battle-tested libraries wrapped by Spring directly. For OAuth specifically, Spring does very little.

Then you have to work to make the libraries all work together. And deal with updates. Spring Boot allows to to update all libraries together, and know that they work together.

[whstl]

For this you setup tests and a CI, which is basic stuff that you can't really skip with Spring.

If you don't want or know how to do this, then there are all the other solutions.

Either way: authentication in a Spring app is the definition of "reinventing the wheel".