Improve documentation of baseline API version to emphasize version must be supported

[yanivnahoum]

From the blog and the docs, here is the expected behavior of the baseline version feature (using the + operator):
When you specify a version with the plus syntax (e.g., version = "1.2+") in a @RequestMapping (or derived annotation like @GetMapping), it declares that the controller method handles requests for that specific version and all subsequent supported versions.

So given the following controller:

@RestController
@RequestMapping(path = "{version}/todos")
public class TodoController {
    @GetMapping(version = "v1.2+")
    public List<Todo> getTodosV1_2() {
        return List.of(new Todo(1L, "Learn Spring Boot 4 - v1.2+", false));
    }
}

and the following configuration:

spring:
  mvc:
    apiversion:
      use:
        path-segment: 0

I'd expect these requests to return 200 OK:

1. /v1.2/todos
2. /v1.2.1/todos

But instead I'm getting a 400 BAD_REQUEST for # 2.
I pushed a small example reproducing the bug (or my error...).

Could you take a look please?

[rstoyanchev]

@yanivnahoum could you edit the description to provide more details? The sample is appreciated, but it is more short lived, and in any case a description is still both helpful and necessary.

[yanivnahoum]

@rstoyanchev Done.

[bclozel]

@yanivnahoum docs also say

The above assumes the request version is a "supported" version, or otherwise it would fail.

Version 1.2.1 doesn't seem to be declared anywhere. Spring Boot also supports the "spring.mvc.apiversion.supported" property. Have you tried listing the expected versions with that property?

[yanivnahoum]

@bclozel According to the docs, it doesn't have to be. Any version semantically greater than 1.2.0 should match 1.2.
At least this is what I see in Spring Framework's docs:

[bclozel]

We need to somehow collect the list of supported versions. Those are collected from annotations and the configuration. Otherwise clients could request version "1.2.999" even if this version doesn't exist officially.

Have you tried my suggestion?

[yanivnahoum]

Ok, I tried this and it works:

spring:
  mvc:
    apiversion:
      use:
        path-segment: 0
      supported:
      - 1.2.1
      - 1.3.0

Now requests to /v1.2.1/todos and /v1.3/todos return 200 OK.
In my opinion, the docs have to be updated to reflect this info. What do you think?