docs: public Observable<ServiceResponse<Void>> startEnvironmentWithServiceResponseAsync(String userName, String environmentId) {
          if (userName == null) {
              throw new IllegalArgumentException("Parameter userName is required and cannot be null.");
          }
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          if (environmentId == null) {
              throw new IllegalArgumentException("Parameter environmentId is required and cannot be null.");
          }
          EnvironmentOperationsPayload environmentOperationsPayload = new EnvironmentOperationsPayload();
          environmentOperationsPayload.withEnvironmentId(environmentId);
          Observable<Response<ResponseBody>> observable = service.startEnvironment(userName, this.client.apiVersion(), this.client.acceptLanguage(), environmentOperationsPayload, this.client.userAgent());
          return client.getAzureClient().getPostOrDeleteResultAsync(observable, new TypeToken<Void>() { }.getType());
      }