public async Task DetectedLanguageNullIso6391Name() { using var stream = new MemoryStream(Encoding.UTF8.GetBytes(@" { ""kind"": ""LanguageDetectionResults"", ""results"": { ""documents"": [ { ""id"": ""1"", ""detectedLanguage"": { ""name"": ""English"", ""iso6391Name"": null, ""confidenceScore"": 1 }, ""warnings"": [] } ], ""errors"": [], ""modelVersion"": ""2020 -07-01"" } }")); var mockResponse = new MockResponse(200); mockResponse.ContentStream = stream; var mockTransport = new MockTransport(new[] { mockResponse }); var client = CreateTestClient(mockTransport); var documents = new List <DetectLanguageInput> { new DetectLanguageInput("1", "Hello world") { CountryHint = "us", } }; DetectLanguageResultCollection response = await client.DetectLanguageBatchAsync(documents); Assert.IsNotNull(response.FirstOrDefault().PrimaryLanguage.Name); Assert.IsNull(response.FirstOrDefault().PrimaryLanguage.Iso6391Name); }