ng-openapi-gen broken respose types

comparsion.ts

export class ContractTypesService extends BaseService {
  contractTypesGet$Json$ResponseOLD(params?: {

  }): Observable<StrictHttpResponse<{ [key: string]: string }>> {

    const rb = new RequestBuilder(this.rootUrl, ContractTypesService.ContractTypesGetPath, 'get');
    if (params) {


    }
    return this.http.request(rb.build({
      // FIXME: PROBLEM IS HERE
      responseType: 'json',
      accept: 'application/json'
    })).pipe(
      filter((r: any) => r instanceof HttpResponse),
      map((r: HttpResponse<any>) => {
        return r as StrictHttpResponse<{ [key: string]: string }>;
      })
    );
  }
        
  contractTypesGet$Json$ResponseNEW(params?: {

  }): Observable<StrictHttpResponse<{ [key: string]: string }>> {

    const rb = new RequestBuilder(this.rootUrl, ContractTypesService.ContractTypesGetPath, 'get');
    if (params) {


    }
    return this.http.request(rb.build({
      // FIXME: PROBLEM IS HERE
      responseType: 'text',
      accept: 'text/json'
    })).pipe(
      filter((r: any) => r instanceof HttpResponse),
      map((r: HttpResponse<any>) => {
        return r as StrictHttpResponse<{ [key: string]: string }>;
      })
    );
  }
}

swagger.json

{
  "openapi": "3.0.1",
  "info": {
    "title": "Enumeration API",
    "version": "v1"
  },
  "servers": [
    {
      "url": "http://localhost"
    }
  ],
  "paths": {
    "/Countries": {
      "get": {
        "tags": [
          "Countries"
        ],
        "responses": {
          "200": {
            "description": "Success",
            "content": {
              "text/plain": {
                "schema": {
                  "type": "object",
                  "additionalProperties": {
                    "type": "string"
                  }
                }
              },
              "application/json": {
                "schema": {
                  "type": "object",
                  "additionalProperties": {
                    "type": "string"
                  }
                }
              },
              "text/json": {
                "schema": {
                  "type": "object",
                  "additionalProperties": {
                    "type": "string"
                  }
                }
              }
            }
          }
        }
      }
    }
  },
  "components": { }
}