Exactly. For example, if you're (still) using Spring MVC, what gets called in your backend on a given action attribute in your JSP or Thymeleaf or whatever template, is expressed through your method signature and lots of annotations where the order of arguments matter eg. some magic attributes must come right after others. All you see in your debugger, though, is that your request hangs in some nested and chained handler and reflection monstrosity driven by annotations and who knows what. Took multiple developers a day or two to figure out, each on their own.

It's not that Spring is badly coded or something, I just don't need these surprises and the magical thinking surrounding newbie Spring Boot projects.

The source code of Spring itself. I know Spring internals - there’s no dark magic there and reference guide describes it well. DI is straightforward, MVC - not perfect, but generally easy, Security - well, it has design problems, but they are not related to annotations.