Maven openapi generator plugin generates Auth classes

Question

I'm building a very simple API with maven plugin configuration here. But it generates some Authentication classes (auth package and some other classes like StringUtil, JSON) I've never defined in my configuration. I don't want all these classes, where do they come from ? :

Here is my student.yaml input file :

openapi: 3.0.0
info:
  title: student API
  description: student demo API by Anthony Errera
  version: 1.0.0
paths:
  /student:
    description: Student Resource
    get:
      description: operation to fetch student
      parameters:
        - in: query
          name: studentname
          required: true
          schema:
            type: string
      responses:
        200:
          description: Success response
          content:
            application/json:
              schema:
                type: array
                items:
                  properties:
                    StudentID:
                      type: integer
                      example: 3
                    StudentName:
                      type: string
                      example: toto
    post:
      description: add a student
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/student'
      responses:
        201:
          description: student created
components:
  schemas:
    student:
      type:  object
      properties:
        StudentID:
          type: integer
          example: 3
        StudentName:
          type: string
          example: toto