[BUG] Object as query paramenter

Description

Just found an issue when using an Object as Query-Parameter.
When using e.g. swagger-codegen (Java), it's possible to do the following:

/xyz:
    get:
      parameters:
      - in: query
        required: false
        name: someBoolean
        schema:
          type: boolean
      - in: query
        name: someObject
        required: false
        schema:
          $ref: '#/components/schemas/SomeObjectDto'

In this case e.g. Swagger uses all properties of SomeObjectDto as Query Parameter.

In your lib the toString-Method of each Object is used as query parameter. E.g.:

@override
String toString() => 'SomeObjectDto[propA=$propA, propB=$propB]';

I think this should get corrected :)

openapi-generator version

3.2.1

OpenAPI declaration file content or url

Start with the Java client generation path for query-parameter serialization and reproduce the OpenAPI declaration using the SomeObjectDto reference. Compare the generated request for an object parameter with the Swagger behavior; done means the object's properties are represented as query parameters instead of using the object's toString() value.