[Kotlin][Spring] Fix RequestPart handling for multipart request

[zakupower]

fix for #15251

When generating a Multipart request where model is used instead of binary or basic field, it should be annotated with @Multipart instead of @RequestParam.

This was already fixed for the Java-Spring generator with #14357, but is still present in the Kotlin-Spring generator.

Link to Spring Documentation supporting this

Example Spec:

openapi: '3.0.1'
info:
  version: 1.0.0
  title: MultipartFile test
paths:
  /multipart-mixed:
    post:
      tags:
        - multipart
      description: Mixed MultipartFile test
      operationId: multipartMixed
      requestBody:
        content:
          multipart/form-data:
            schema:
              type: object
              required:
                - status
                - file
              properties:
                status:
                  $ref: '#/components/schemas/MultipartMixedStatus'
                marker:
                  description: "additional object"
                  type: object
                  properties:
                    name:
                      type: string
                file:
                  description: "a file"
                  type: string
                  format: binary
      responses:
        '204':
          description: Successful operation
components:
  schemas:
    MultipartMixedStatus:
      description: "additional field as Enum"
      type: string
      enum:
        - ALLOWED
        - IN_PROGRESS
        - REJECTED
      example: REJECTED

Expected Output:

@RestController
@Validated
@RequestMapping("\${api.base-path:}")
class MultipartMixedApiController() {

    @Operation(
        summary = "",
        operationId = "multipartMixed",
        description = """Mixed MultipartFile test""",
        responses = [
            ApiResponse(responseCode = "204", description = "Successful operation") ]
    )
    @RequestMapping(
        method = [RequestMethod.POST],
        value = ["/multipart-mixed"],
        consumes = ["multipart/form-data"]
    )
    fun multipartMixed(@Parameter(description = "", required = true, schema = Schema(allowableValues = ["ALLOWED", "IN_PROGRESS", "REJECTED"])) @RequestParam(value = "status", required = true) status: MultipartMixedStatus ,@Parameter(description = "a file") @Valid @RequestPart("file", required = true) file: org.springframework.core.io.Resource,@Parameter(description = "") @RequestPart(value = "marker", required = false) marker: MultipartMixedRequestMarker? ): ResponseEntity<Unit> {
        return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
    }
}

Actual output with version 7.7.0:

@RestController
@Validated
@RequestMapping("\${api.base-path:}")
class MultipartMixedApiController() {

    @Operation(
        summary = "",
        operationId = "multipartMixed",
        description = """Mixed MultipartFile test""",
        responses = [
            ApiResponse(responseCode = "204", description = "Successful operation") ]
    )
    @RequestMapping(
        method = [RequestMethod.POST],
        value = ["/multipart-mixed"],
        consumes = ["multipart/form-data"]
    )
    fun multipartMixed(@Parameter(description = "", required = true, schema = Schema(allowableValues = ["ALLOWED", "IN_PROGRESS", "REJECTED"])) @RequestParam(value = "status", required = true) status: MultipartMixedStatus ,@Parameter(description = "a file") @Valid @RequestPart("file", required = true) file: org.springframework.core.io.Resource,@Parameter(description = "") @RequestParam(value = "marker", required = false) marker: MultipartMixedRequestMarker? ): ResponseEntity<Unit> {
        return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
    }
}

Specifically look at the marker parameter generation

PR checklist

• Read the contribution guidelines.
• Pll Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh ./bin/configs/*.yaml
  ./bin/utils/export_docs_generators.sh
  

  (For Windows users, please run the script in Git BASH)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.6.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

@jimschubert @dr4ke616 @karismann @Zomzog @andrewemery @4brunu @yutaka0m @stefankoppier

[zakupower]

Any reason this is not being merged? (Don't want to be rude or impatient, just want to know if I can do something to get this to be merged before next version)

[wing328]

@zakupower thanks for the PR. Can you please add a test by first adding a config file similar to ./bin/configs/kotlin-spring-boot-bigdecimal-default.yaml (e.g. kotlin-spring-multipart-request-model.yaml`) ?

Then create a test spec similar to modules/openapi-generator/src/test/resources/3_0/issue_14584_bigdecimal_default.yaml

Then generate the samples (run the ./bin/generate-samples.sh command twice)

And update the .github/workflows/samples-kotlin-server.yaml with the path to the new sample folder (e.g. samples/server/petstore/kotlin-springboot-multipart-request-model)

[zakupower]

@wing328 I think I made all the changes that you requested.

[wing328]

https://github.com/OpenAPITools/openapi-generator/actions/runs/9990043197/job/27617120054?pr=19058 not related to this PR

i'll merge later today if no one else has feedback on this PR.

thanks again for the PR

[zakupower]

Thank you as well for your quick responses and hard work on the project!