Add cancelled property to taskinfo (#5803)

Author: stevejgordon

src/Nest/Cluster/TaskManagement/GetTask/TaskInfo.cs

@@ -17,6 +17,9 @@ public class TaskInfo
 		[DataMember(Name ="cancellable")]
 		public bool Cancellable { get; internal set; }
 
+		[DataMember(Name ="cancelled")]
+		public bool? Cancelled { get; internal set; }
+
 		[DataMember(Name ="children")]
 		public IReadOnlyCollection<TaskInfo> Children { get; internal set; } = EmptyReadOnly<TaskInfo>.Collection;
 

tests/Tests/Cluster/TaskManagement/GetTask/GetTaskApiTests.cs

@@ -53,6 +53,12 @@ protected override void ExpectResponse(GetTaskResponse response)
 			task.StartTimeInMilliseconds.Should().BeGreaterThan(0);
 			task.RunningTimeInNanoseconds.Should().BeGreaterThan(0);
 			task.Cancellable.Should().BeTrue();
+			
+			if (Cluster.ClusterConfiguration.Version >= "7.14.0")
+			{
+				task.Cancelled.HasValue.Should().BeTrue();
+				task.Cancelled.Should().BeFalse();
+			}
 		}
 
 		protected override void IntegrationSetup(IElasticClient client, CallUniqueValues values)
@@ -129,6 +135,12 @@ protected override void ExpectResponse(GetTaskResponse response)
 			task.RunningTimeInNanoseconds.Should().BeGreaterThan(0);
 			task.Cancellable.Should().BeTrue();
 
+			if (Cluster.ClusterConfiguration.Version >= "7.14.0")
+			{
+				task.Cancelled.HasValue.Should().BeTrue();
+				task.Cancelled.Should().BeFalse();
+			}
+
 			var reindexResponse = response.GetResponse<ReindexOnServerResponse>();
 			reindexResponse.Should().NotBeNull();
 			reindexResponse.Took.Should().BeGreaterThan(0);