Your code-first API needs validation
When you start a project you might tend to do code first API as this is a well-known territory for most developers, especially with frameworks like Spring Boot which use powerful annotations to generate your API and specifications.
In a matter of a few lines, you have a simple CRUD API up and running. But that’s not the end of the story, people need to consume it next. And as they are looking at consuming your API the first thing they will turn to is your documentation, specification, and associated testing UI.
You would think that the code-first approach and auto-generation of your OpenAPI specification got you covered. Sadly most of the time your specification will be invalid.