Add categorization analyzer to defaults on ml info response (#4408)

Relates: #4341, elastic/elasticsearch#49545

Author: russcam

src/Nest/XPack/MachineLearning/MachineLearningInfo/MachineLearningInfoResponse.cs

@@ -1,4 +1,5 @@
-using System.Runtime.Serialization;
+using System.Collections.Generic;
+using System.Runtime.Serialization;
 
 namespace Nest
 {
@@ -33,6 +34,18 @@ public class AnomalyDetectors
 
 		[DataMember(Name = "model_snapshot_retention_days")]
 		public int ModelSnapshotRetentionDays { get; internal set; }
+
+		[DataMember(Name = "categorization_analyzer")]
+		public CategorizationAnalyzer CategorizationAnalyzer { get; internal set; }
+	}
+
+	public class CategorizationAnalyzer
+	{
+		[DataMember(Name = "tokenizer")]
+		public string Tokenizer { get; internal set; }
+
+		[DataMember(Name = "filter")]
+		public IReadOnlyCollection<ITokenFilter> Filter { get; internal set; }
 	}
 
 	public class Datafeeds

tests/Tests/XPack/MachineLearning/MachineLearningInfo/MachineLearningInfoApiTests.cs

@@ -34,11 +34,20 @@ protected override void ExpectResponse(MachineLearningInfoResponse response)
 		{
 			response.ShouldBeValid();
 
-			response.Defaults.AnomalyDetectors.ModelMemoryLimit.Should().Be("1gb");
-			response.Defaults.AnomalyDetectors.CategorizationExamplesLimit.Should().Be(4);
-			response.Defaults.AnomalyDetectors.ModelSnapshotRetentionDays.Should().Be(1);
+			var anomalyDetectors = response.Defaults.AnomalyDetectors;
+			anomalyDetectors.ModelMemoryLimit.Should().Be("1gb");
+			anomalyDetectors.CategorizationExamplesLimit.Should().Be(4);
+			anomalyDetectors.ModelSnapshotRetentionDays.Should().Be(1);
 
 			response.Defaults.Datafeeds.ScrollSize.Should().Be(1000);
+
+			if (Cluster.ClusterConfiguration.Version >= "7.6.0")
+			{
+				var analyzer = anomalyDetectors.CategorizationAnalyzer;
+				analyzer.Should().NotBeNull();
+				analyzer.Tokenizer.Should().Be("ml_classic");
+				analyzer.Filter.Should().NotBeNullOrEmpty();
+			}
 		}
 	}
 }