[BUG][spring][spring-boot] org.springframework.core.io.Resource cannot be converted to org.springframework.web.multipart.MultipartFile

Bug Report Checklist

This is a dup of #18345 because #18345 is closed but is still present (7.11.0)

Description

  /validate:
    post:
      description: 'Validate Config ZIP'
      operationId: 'validate-config-zip'
      tags:
        - 'config'
      responses:
        200:
          description: 'OK'
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ValidateConfigResult'
      requestBody:
        required: true
        content:
          application/zip:
            schema:
              type: string
              format: binary

Generates invalid java code:

    /**
     * POST /validate
     * Validate Config ZIP
     *
     * @param body  (required)
     * @return OK (status code 200)
     */
    @Operation(
        operationId = "validateConfigZip",
        description = "Validate Config ZIP",
        tags = { "config" },
        responses = {
            @ApiResponse(responseCode = "200", description = "OK", content = {
                @Content(mediaType = "application/json", schema = @Schema(implementation = ValidateConfigResultModel.class))
            })
        }
    )
    @RequestMapping(
        method = RequestMethod.POST,
        value = "/validate",
        produces = { "application/json" },
        consumes = { "application/zip" }
    )
    
    default ResponseEntity<ValidateConfigResultModel> _validateConfigZip(
        @Parameter(name = "body", description = "", required = true) @Valid @RequestBody org.springframework.core.io.Resource body
    ) {
        return validateJourneyConfigVersionZip(body);
    }

    // Override this method
    default  ResponseEntity<ValidateConfigResultModel> validateConfigZip(MultipartFile body) {
        getRequest().ifPresent(request -> {
            for (MediaType mediaType: MediaType.parseMediaTypes(request.getHeader("Accept"))) {
                if (mediaType.isCompatibleWith(MediaType.valueOf("application/json"))) {
                    String exampleString = "{ \"schemaValidationErrors\" : [ \"schemaValidationErrors\", \"schemaValidationErrors\" ], \"resourceInitializationErrors\" : [ \"resourceInitializationErrors\", \"resourceInitializationErrors\" ] }";
                    ApiUtil.setExampleResponse(request, "application/json", exampleString);
                    break;
                }
            }
        });
        return new ResponseEntity<>(HttpStatus.NOT_IMPLEMENTED);

    }

incompatible types: org.springframework.core.io.Resource cannot be converted to org.springframework.web.multipart.MultipartFile

As seen above, RequestMapping method uses Spring's Resource object but the delegate method expects a MultipartFile object which leads to a compiler error.

openapi-generator version

7.2.0
7.7.0
7.11.0

OpenAPI declaration file content or url

Generation Details

<generatorName>spring</generatorName>
<library>spring-boot</library>

Steps to reproduce

Related issues/PRs

#18345
#12453

Suggest a fix

Start by reviewing the Spring generator's spring-boot output for the shown /validate operation, then compare the behavior described in related issues #18345 and #12453. Done means the generated Java code uses compatible parameter types and compiles for an application/zip request body.