[Backport 8.4] Add support for geo distance sorting.

src/Elastic.Clients.Elasticsearch/Types/SortOptions.cs

@@ -18,7 +18,7 @@ public partial class SortOptions
 internal sealed class SortOptionsConverter : JsonConverter<SortOptions>
 {
 	// We manually define this converter since we simplify SortCombinations union from the spec as SortOptions instance.
-	// This requires a custom read method to handle deserialisation of the potential union JSON as specified.
+	// This requires a custom read method to handle deserialization of the potential union JSON as specified.
 
 	public override SortOptions Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
 	{
@@ -53,6 +53,13 @@ public override SortOptions Read(ref Utf8JsonReader reader, Type typeToConvert,
 				return new SortOptions(propertyName, variant);
 			}
 
+			if (propertyName == "_geo_distance")
+			{
+				var variant = JsonSerializer.Deserialize<GeoDistanceSort?>(ref reader, options);
+				reader.Read();
+				return new SortOptions(propertyName, variant);
+			}
+
 			// For field sorts, the property name will be the field name
 			{
 				var variant = JsonSerializer.Deserialize<FieldSort>(ref reader, options);
@@ -104,6 +111,9 @@ public override void Write(Utf8JsonWriter writer, SortOptions value, JsonSeriali
 			case "_script":
 				JsonSerializer.Serialize<ScriptSort>(writer, (ScriptSort)value.Variant, options);
 				break;
+			case "_geo_distance":
+				JsonSerializer.Serialize<GeoDistanceSort>(writer, (GeoDistanceSort)value.Variant, options);
+				break;
 			default:
 				JsonSerializer.Serialize<FieldSort>(writer, (FieldSort)value.Variant, options);
 				break;

src/Elastic.Clients.Elasticsearch/_Generated/Types/Enums/Enums.NoNamespace.g.cs

@@ -451,6 +451,48 @@ public override void Write(Utf8JsonWriter writer, FieldSortNumericType value, Js
 	}
 }
 
+[JsonConverter(typeof(GeoDistanceTypeConverter))]
+public enum GeoDistanceType
+{
+	[EnumMember(Value = "plane")]
+	Plane,
+	[EnumMember(Value = "arc")]
+	Arc
+}
+
+internal sealed class GeoDistanceTypeConverter : JsonConverter<GeoDistanceType>
+{
+	public override GeoDistanceType Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+	{
+		var enumString = reader.GetString();
+		switch (enumString)
+		{
+			case "plane":
+				return GeoDistanceType.Plane;
+			case "arc":
+				return GeoDistanceType.Arc;
+		}
+
+		ThrowHelper.ThrowJsonException();
+		return default;
+	}
+
+	public override void Write(Utf8JsonWriter writer, GeoDistanceType value, JsonSerializerOptions options)
+	{
+		switch (value)
+		{
+			case GeoDistanceType.Plane:
+				writer.WriteStringValue("plane");
+				return;
+			case GeoDistanceType.Arc:
+				writer.WriteStringValue("arc");
+				return;
+		}
+
+		writer.WriteNullValue();
+	}
+}
+
 [JsonConverter(typeof(HealthStatusConverter))]
 public enum HealthStatus
 {