HandlerMethodValidationException.Visitor should support RequestBody with method parameter constraints

[jarzynp]

Environment

Spring Boot: 3.4.3
Spring Web: 6.2.3
Java: 17

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Expected Behavior

When a @RequestBody value is invalid, HandlerMethodValidationException.Visitor should call the appropriate method.

Observed Behavior

Instead, HandlerMethodValidationException.Visitor throws IllegalStateException with "Expected ParameterErrors" message.

Example code

@Target({ElementType.TYPE_USE, ElementType.PARAMETER, ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = {})
@NotEmpty
@Pattern(regexp = "^[a-z0-9]{1,10}$", message = ResId.RULES)
public @interface ResId {

    String RULES = "Identifier doesn't follow defined rules.";

    String message() default RULES;

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};

}

@RestController
@RequestMapping("/api")
public class Controller {

    @PostMapping("/{id}/modify")
    public ResponseEntity<Object> modify(
        @PathVariable @ResId final String id,
        @RequestBody @Valid final List<@ResId String> linkedResourceIds) {
        return ResponseEntity.noContent();
    }

}

Example request

HTTP Method = POST
Request URI = /api/foo/modify
Body = ["aasfw44t23gsdge4g3wcsdf43"]

---

Insights

In HandlerMethodValidationException#visitResults(HandlerMethodValidationException.Visitor):

RequestBody requestBody = param.getParameterAnnotation(RequestBody.class);
if (requestBody != null) {
	visitor.requestBody(requestBody, asErrors(result));
	continue;
}

the condition if (requestBody != null) is true, but the asErrors(result) is throwing the exception because in this case result is not an instance of ParameterErrors but ParameterValidationResult.