Fix distance_feature query serialization (#4488) (#4489)

Closes #4487

Co-authored-by: Russ Cam <russ.cam@elastic.co>

Author: github-actions[bot]

docs/query-dsl/specialized/distance-feature/distance-feature-query-usage.asciidoc

@@ -78,6 +78,7 @@ An instance of `GeoCoordinate` can be provided as the `origin`, with `pivot` bei
 ----
 q
 .DistanceFeature(rf => rf
+    .Name("name")
     .Boost(1.1)
     .Field(f => f.LeadDeveloper.Location)
     .Origin(new GeoCoordinate(70, -70))
@@ -91,6 +92,7 @@ q
 ----
 new DistanceFeatureQuery()
 {
+    Name = "name",
     Boost = 1.1,
     Field = Infer.Field<Project>(f => f.LeadDeveloper.Location),
     Origin = new GeoCoordinate(70, -70),
@@ -103,6 +105,7 @@ new DistanceFeatureQuery()
 ----
 {
   "distance_feature": {
+    "_name": "name",
     "boost": 1.1,
     "field": "leadDeveloper.location",
     "origin": [

src/Nest/QueryDsl/Specialized/DistanceFeature/DistanceFeatureQuery.cs

@@ -90,6 +90,20 @@ public void Serialize(ref JsonWriter writer, IDistanceFeatureQuery value, IJsonF
 
 			writer.WriteBeginObject();
 
+			if (!string.IsNullOrEmpty(value.Name))
+			{
+				writer.WritePropertyName("_name");
+				writer.WriteString(value.Name);
+				writer.WriteValueSeparator();
+			}
+
+			if (value.Boost.HasValue)
+			{
+				writer.WritePropertyName("boost");
+				writer.WriteDouble(value.Boost.Value);
+				writer.WriteValueSeparator();
+			}
+
 			writer.WritePropertyName("field");
 			var fieldFormatter = formatterResolver.GetFormatter<Field>();
 			fieldFormatter.Serialize(ref writer, value.Field, formatterResolver);
@@ -101,13 +115,6 @@ public void Serialize(ref JsonWriter writer, IDistanceFeatureQuery value, IJsonF
 
 			writer.WritePropertyName("pivot");
 			PivotUnionFormatter.Serialize(ref writer, value.Pivot, formatterResolver);
-			writer.WriteValueSeparator();
-
-			if (value.Boost.HasValue)
-			{
-				writer.WritePropertyName("boost");
-				writer.WriteDouble(value.Boost.Value);
-			}
 
 			writer.WriteEndObject();
 		}
@@ -117,7 +124,8 @@ public void Serialize(ref JsonWriter writer, IDistanceFeatureQuery value, IJsonF
 			{ "field", 0 },
 			{ "origin", 1 },
 			{ "pivot", 2 },
-			{ "boost", 3 }
+			{ "boost", 3 },
+			{ "_name", 4 }
 		};
 
 		public IDistanceFeatureQuery Deserialize(ref JsonReader reader, IJsonFormatterResolver formatterResolver)
@@ -145,6 +153,9 @@ public IDistanceFeatureQuery Deserialize(ref JsonReader reader, IJsonFormatterRe
 						case 3:
 							query.Boost = reader.ReadDouble();
 							break;
+						case 4:
+							query.Name = reader.ReadString();
+							break;
 					}
 				}
 				else

tests/Tests.Reproduce/GitHubIssue4487.cs

@@ -0,0 +1,28 @@
+using Elastic.Xunit.XunitPlumbing;
+using Elasticsearch.Net;
+using FluentAssertions;
+using Nest;
+using Tests.Core.Client;
+
+namespace Tests.Reproduce
+{
+	public class GitHubIssue4487
+	{
+		[U]
+		public void CanSerializeDistanceFeatureQueryWithoutBoost()
+		{
+			var searchRequest = new SearchRequest
+			{
+				Query = new DistanceFeatureQuery
+				{
+					Field = "foo",
+					Origin = new GeoCoordinate(90, 90),
+					Pivot = Distance.Meters(100)
+				}
+			};
+
+			var json = TestClient.DefaultInMemoryClient.RequestResponseSerializer.SerializeToString(searchRequest);
+			json.Should().Be(@"{""query"":{""distance_feature"":{""field"":""foo"",""origin"":[90.0,90.0],""pivot"":""100m""}}}");
+		}
+	}
+}

tests/Tests/QueryDsl/Specialized/DistanceFeature/DistanceFeatureQueryUsageTests.cs

@@ -86,6 +86,7 @@ public DistanceFeatureDistanceQueryUsageTests(ReadOnlyCluster i, EndpointUsage u
 
 		protected override QueryContainer QueryInitializer => new DistanceFeatureQuery()
 		{
+			Name = "name",
 			Boost = 1.1,
 			Field = Infer.Field<Project>(f => f.LeadDeveloper.Location),
 			Origin = new GeoCoordinate(70, -70),
@@ -97,6 +98,7 @@ public DistanceFeatureDistanceQueryUsageTests(ReadOnlyCluster i, EndpointUsage u
 			{
 				distance_feature = new
 				{
+					_name = "name",
 					boost = 1.1,
 					field = "leadDeveloper.location",
 					origin = new [] { -70.0, 70.0 },
@@ -106,6 +108,7 @@ public DistanceFeatureDistanceQueryUsageTests(ReadOnlyCluster i, EndpointUsage u
 
 		protected override QueryContainer QueryFluent(QueryContainerDescriptor<Project> q) => q
 			.DistanceFeature(rf => rf
+				.Name("name")
 				.Boost(1.1)
 				.Field(f => f.LeadDeveloper.Location)
 				.Origin(new GeoCoordinate(70, -70))