docs: public Observable<ServiceResponse<Page<RoleAssignmentInner>>> listForScopeSinglePageAsync(final String scope, final String filter) {
          if (scope == null) {
              throw new IllegalArgumentException("Parameter scope is required and cannot be null.");
          }
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          return service.listForScope(scope, filter, this.client.apiVersion(), this.client.acceptLanguage(), this.client.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<Page<RoleAssignmentInner>>>>() {
                  @Override
                  public Observable<ServiceResponse<Page<RoleAssignmentInner>>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<PageImpl<RoleAssignmentInner>> result = listForScopeDelegate(response);
                          return Observable.just(new ServiceResponse<Page<RoleAssignmentInner>>(result.body(), result.response()));
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }