BasicErrorController should align with spring.mvc.problemdetails.enabled to support RFC 9457?

[ximinghui]

Description

When RFC 9457 support is enabled via spring.mvc.problemdetails.enabled=true, there is an inconsistency in error response formats.

While exceptions handled by the Spring MVC infrastructure (via ResponseEntityExceptionHandler) correctly return the standard application/problem+json format, the error responses generated by BasicErrorController#error(HttpServletRequest) or DefaultErrorAttributes still return the legacy Spring Boot error format.

Observed Behavior

1. ResponseEntityExceptionHandler returns RFC 9457 format:

{
  "type": "about:blank",
  "title": "Bad Request",
  "status": 400,
  "detail": "Invalid input",
  "instance": "/api/resource"
}

2. BasicErrorController always returns the legacy format:

{
  "timestamp": "2023-10-27T10:00:00.000+00:00",
  "status": 404,
  "error": "Not Found",
  "path": "/api/non-existent"
}

Expected Behavior

When spring.mvc.problemdetails.enabled is set to true, the BasicErrorController (or DefaultErrorAttributes) should also produce a response body that adheres to the RFC 9457 Problem Details specification?

Are there plans to update BasicErrorController to natively support spring.mvc.problemdetails.enabled?