I have an OpenAPI Description with the following structure:

    Schema1:
      type: object
      properties:
        timestamp:
          type: string
          format: date-time
      additionalProperties:
        $ref: "#/components/schemas/Schema2"

When I generate classes via the openapi-generator-maven-plugin with the option <generateAliasAsModel>true</generateAliasAsModel>, the additionalProperties are generated as expected with Map<String, Schema2> additionalProperties.

However, in my OAS description under /v3/api-docs, additionalProperties are not shown in the schema.

{  
    "Schema1": {
        "type": "object",
        "properties": {
          "timestamp": {
            "type": "string",
            "format": "date-time"
          }
       }
    }
}

I used the springdoc-openapi-starter-webmvc-ui for the generation of the OAS docs.

Is there a way to fix that or is there an alternative instead of additionalProperties for a map implementation?