[BUG][Spring] Wrong nullability of method parameters with spring-http-interface library

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

The spring-http-interface library generates method signatures with @NonNull parameters when they should be @Nullable.

For example, consider @RequestParam(value = "foo", required = false, defaultValue = "false") Boolean foo.

When using the default spring-boot library, this makes sense: the developer implements the method body and wants to take advantage of the fact that Spring Boot guarantees the argument is never null.

However, when using the spring-http-interface, this is problematic: now the developer doesn't implement the method body, but invokes the method, and wants to be able to invoke it with null, since Spring will inject the specified defaultValue of false in that case.

openapi-generator version

v7.24.0

OpenAPI declaration file content or url

openapi.yaml

Generation Details

config.json

Steps to reproduce

• in a directory X, create openapi.yaml and config.json with the contents as above
• from within X, run docker run --rm -v .:/local openapitools/openapi-generator-cli:v7.24.0 generate --strict-spec true --input-spec /local/openapi.yaml --generator-name spring --config /local/config.json --output /local/output
• open the generated DefaultApi api: .\output\src\main\java\org\openapitools\api\DefaultApi.java

Related issues/PRs

Suggest a fix

Start with the linked openapi.yaml and config.json, then run the documented Docker generation command and inspect output/src/main/java/org/openapitools/api/DefaultApi.java. Compare the generated spring-http-interface method signatures with the expected behavior for optional request parameters. Done means parameters that may receive null are generated with nullable annotations rather than @NonNull.