Migration guide: platform 2.1.x to 5.0.x

Platform 5.0.1 binds to Across 5.0.1, which is built on top of Spring Boot 2.1.x and Spring Framework 5.1.x. This is a major upgrade with a lot of breaking changes, mostly due to changes inside Spring dependencies.

This guide is not a full overview of all new features and changes in Across or any of its modules. It mainly focuses on upgrade related changes: usually breaking changes or new features that impact application/module configuration.