How to mock HttpTransport.RequestAsync?

[KPGDL]

The documentation is very limited.
https://github.com/elastic/elastic-transport-net/blob/main/README.md#mocking-response-objects-for-testing

var elasticsearchClient = new Mock<ElasticsearchClient>();
var response = TestableResponseFactory.CreateSuccessfulResponse<StringResponse>(new(), 200);
elasticsearchClient.Setup(x => x.Transport.RequestAsync<StringResponse>(
                                     It.IsAny<HttpMethod>(),
                                     It.IsAny<string>(),
                                     It.IsAny<PostData>(),
                                     It.IsAny<RequestParameters>(),
                                     It.IsAny<OpenTelemetryData>(),
                                     It.IsAny<CancellationToken>())).ReturnsAsync(response);

I'm getting this in Moq: Non-overridable members (here: HttpTransport.RequestAsync) may not be used in setup / verification expressions.
@flobernd @stevejgordon @Mpdreamz