[spring] [v3] @RequestPart should use "{{basename}}" instead of "file" and observe "required" attribute

[mladenlukic]

Description

When generating code for Spring for file upload, it's not possible to make the file optional and not mandatory and the name is fixed to 'file'

Swagger-codegen version

3.0.35

Swagger declaration file content or url

/url:
    post:
      operationId: create
      requestBody:
        content:
          multipart/form-data:
            schema:
              type: object
              required: [ name ]
              properties:
                name:
                  type: string
                  minLength: 2
                  maxLength: 20
                graphic:
                  type: string
                  format: binary

Command line used for generation

swagger-codegen generate -i api.yml -l spring

Steps to reproduce

execute the codegen-generate command on a file with multipart/form-data and what you get is:
ResponseEntity<UUID> create(@Parameter(in = ParameterIn.DEFAULT, description = "",schema=@Schema()) @RequestParam(value="name", required=false) String name, @Parameter(description = "file detail") @Valid @RequestPart("file") MultipartFile graphic);

it should be:
ResponseEntity<UUID> create(@Parameter(in = ParameterIn.DEFAULT, description = "",schema=@Schema()) @RequestParam(value="name", required=false) String name, @Parameter(description = "file detail") @Valid @RequestPart("graphic", required=false) MultipartFile graphic);

Related issues/PRs

It's the same issue as this one: #9250