[Spring] Generated server code inconsistent for multipart/form-data request with array of attachments.

Description

Swagger-codegen version

3.0.26

Swagger declaration file content or url

openapi: 3.0.0
info:  
  version: "0.1"
  title: testbug
paths:
  /testbug:
    post:
      requestBody:
        content:
          multipart/form-data:
            schema:
              type: object
              properties:
                attachment:
                  type: string
                  format: binary
                attachments:
                  items:
                    type: string
                    format: binary
      responses:
        '201':
          description: Successful response.
          content:
            text/plain:
              schema:
                type: string

Command line used for generation

java -jar .\swagger-codegen-cli-3.0.26.jar generate -l spring -i testbug.yaml -o testbug

Steps to reproduce

java -jar .\swagger-codegen-cli-3.0.26.jar generate -l spring -i testbug.yaml -o testbug

This generates following server-side code TestbugApi.java for above operation /testbug:

import org.springframework.core.io.Resource;
import org.springframework.web.multipart.MultipartFile;
...
public interface TestbugApi {

    @Operation(summary = "", description = "", tags={  })
    @ApiResponses(...})
    @RequestMapping(value = "/testbug",
        produces = { "text/plain" }, 
        consumes = { "multipart/form-data" }, 
        method = RequestMethod.POST)
    ResponseEntity<String> testbugPost(
      @Parameter(description = "file detail") @Valid @RequestPart("file") MultipartFile attachment, 
      @Parameter(in = ParameterIn.DEFAULT, description = "",schema=@Schema()) 
          @RequestParam(value="attachments", required=false)  List<Resource> attachments);
}

So for the single attachment it generates a parameter of type MultipartFile that contains getters to retrieve the Content-Disposition name attribute and the Content-Type header for the related MIME part (OK).

However for the list of attachments we get a list of type Resource that doesn't contain getters to retrieve the Content-Disposition name attribute and neither the Content-Type header for the related MIME part (NOK).

Related issues/PRs

Not found.

Suggest a fix/enhancement

None.

Reproduce the issue with the provided OpenAPI declaration and swagger-codegen-cli command, then inspect the generated Spring server interface in TestbugApi.java. Compare the MultipartFile attachment parameter with the List attachments parameter; done means the generated array-of-attachments signature preserves the expected multipart file metadata access consistently.