Add architecture stats to cluster node stats (#5338)

Author: stevejgordon

src/Nest/Cluster/ClusterStats/ClusterNodesStats.cs

@@ -42,6 +42,9 @@ public class ClusterNodesStats
 
 		[DataMember(Name = "ingest")]
 		public ClusterIngestStats Ingest { get; internal set; }
+
+		[DataMember(Name = "architectures")]
+		public IReadOnlyCollection<ArchitectureStats> Architectures { get; internal set; }
 	}
 
 	public class NodePackagingType
@@ -255,4 +258,14 @@ public class ClusterProcessorStats
 		[DataMember(Name ="time_in_millis")]
 		public long TimeInMilliseconds { get; set; }
 	}
+
+	[DataContract]
+	public class ArchitectureStats
+	{
+		[DataMember(Name = "arch")]
+		public string Architecture { get; set; }
+
+		[DataMember(Name = "count")]
+		public int Count { get; set; }
+	}
 }

tests/Tests/Cluster/ClusterStats/ClusterStatsApiTests.cs

@@ -100,6 +100,14 @@ protected void Assert(ClusterNodesStats nodes)
 
 			if (Cluster.ClusterConfiguration.Version >= "7.6.0")
 				nodes.Ingest.Should().NotBeNull();
+			
+			if (Cluster.ClusterConfiguration.Version >= "7.12.0")
+			{
+				nodes.Architectures.Should().NotBeNull();
+				nodes.Architectures.Count.Should().BeGreaterThan(0);
+				nodes.Architectures.First().Architecture.Should().NotBeNullOrEmpty();
+				nodes.Architectures.First().Count.Should().BeGreaterThan(0);
+			}
 		}
 
 		protected void Assert(ClusterIndicesStats indices)