Wrong dynamic query parameter names in spring

Description

Hello, I'm trying to generate dynamic query parameter names in spring boot, I'm trying to get this
https://example.com/api_v3/v3/filters?static_arg=smth&freeform_arg1=value1&freeform_arg2=value2

but instead generated url is
https://example.com/api_v3/v3/filters?static_arg=smth&applied_filters=class%20AppliedFilter%20%7B%0A%20%20%20%20%7Barg2%3Dvalue2%2C%20arg1%3Dvalue1%7D%0A%7D

Swagger-codegen version

3.0.55

Swagger declaration file content or url

  /api_v3/v3/filters:
    get:
      parameters:
        - $ref: '#/components/parameters/static_arg'
        - in: query
          name: applied_filters
          schema:
            $ref: "#/components/schemas/AppliedFilter"
      responses:
        '200':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/FilterResponseV3'

components:

  schemas:
    AppliedFilter:
      type: object
      additionalProperties:
        type: string

Suggest a fix/enhancement

Maybe it's a wrong specification declaration, or a bug. Please, help!

Start with the supplied OpenAPI declaration for /api_v3/v3/filters and its AppliedFilter schema, then reproduce generation with Swagger Codegen 3.0.55 for Spring. Compare the generated request construction with the expected freeform_arg1 and freeform_arg2 query parameters; done means the generated URL uses those dynamic names instead of serializing AppliedFilter as applied_filters.