[Java/spring] multipart/form-data in requestBody does not generate anything

Since 3.0.21, code generation for multipart/form-data in requestBody does not generate any @RequestPart input param in the java interface.

    post:
      tags:
        - ads  dataset request
      summary: ...
      description: ...
      operationId: createDatasetRequest
      security:
        - basicAuth: []
      parameters:
        - in: query
          name: scheduling
          schema:
            type: string
            example: '0 8 * * *'
        - in: query
          name: startDate
          schema:
            type: string
            format: date-time
        - in: query
          name: endDate
          schema:
            type: string
            format: date-time
      requestBody:
        content:
          multipart/form-data:
            schema:
              properties:
                file:
                  type: string
                  format: binary
        required: true
      responses:
        '201':
          description: ...
          content:
            text/plain:
              schema:
                type: string
                example: e59f329a-d911-4bd1-89ee-e8e922ca632c
        default:
          description: ...
          content:
            application/problem+json:
              schema:
                $ref: '#/components/schemas/ProblemDTO'

It was working in 3.0.20.

Start by reproducing the supplied OpenAPI multipart/form-data example with the Java Spring generator, comparing output from 3.0.20 and 3.0.21. Trace the generator path responsible for requestBody parameters and verify that the generated interface includes the file input as an @RequestPart parameter.