feat: add support for SipHeaders in Answer webhook

Author: Tr00d

Vonage.Test/Voice/Data/Answer.json

@@ -2,5 +2,7 @@
   "from": "442079460000",
   "to": "447700900000",
   "uuid": "aaaaaaaa-bbbb-cccc-dddd-0123456789ab",
-  "conversation_uuid": "CON-aaaaaaaa-bbbb-cccc-dddd-0123456789ab"
+  "conversation_uuid": "CON-aaaaaaaa-bbbb-cccc-dddd-0123456789ab",
+  "SipHeader_X-Test": "test",
+  "SipHeader_X-Value": "value"
 }

Vonage.Test/Voice/WebhookStructsTest.cs

@@ -1,5 +1,6 @@
 #region
 using System;
+using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
 using FluentAssertions;
@@ -31,15 +32,6 @@ public class WebhookStructsTest
         "yyyy-MM-dd'T'HH:mm:ss.fff'Z'",
         CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal);
 
-    private static Answer ExpectedAnswer =>
-        new Answer
-        {
-            From = From,
-            To = To,
-            Uuid = Uuid,
-            ConversationUuid = ConversationId,
-        };
-
     private static Answered ExpectedAnswered =>
         new Answered
         {
@@ -230,11 +222,27 @@ public class WebhookStructsTest
             SipCode = 404,
         };
 
+    private static void VerifyAnswer(Answer input)
+    {
+        input.From.Should().Be(From);
+        input.To.Should().Be(To);
+        input.Uuid.Should().Be(Uuid);
+        input.ConversationUuid.Should().Be(ConversationId);
+        input.SipHeaders.Should().BeEquivalentTo(new Dictionary<string, string>
+        {
+            {"SipHeader_X-Test", "test"},
+            {"SipHeader_X-Value", "value"},
+        });
+    }
+
     [Theory]
     [InlineData(JsonSerializerType.Newtonsoft)]
     [InlineData(JsonSerializerType.SystemTextJson)]
-    public void DeserializeAnswer(JsonSerializerType serializer) =>
-        Deserialize<Answer>(ReadJson("Voice/Data/Answer.json"), serializer).Should().BeEquivalentTo(ExpectedAnswer);
+    public void DeserializeAnswer(JsonSerializerType serializer)
+    {
+        var answer = Deserialize<Answer>(ReadJson("Voice/Data/Answer.json"), serializer);
+        VerifyAnswer(answer);
+    }
 
     [Theory]
     [InlineData(JsonSerializerType.Newtonsoft)]

Vonage/Voice/AnswerWebhooks/Answer.cs

@@ -1,6 +1,10 @@
 #region
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.Json;
 using System.Text.Json.Serialization;
 using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
 using Vonage.Voice.EventWebhooks;
 #endregion
 
@@ -35,4 +39,34 @@ public class Answer : EventBase
     [JsonProperty("conversation_uuid")]
     [JsonPropertyName("conversation_uuid")]
     public string ConversationUuid { get; set; }
+
+    /// <summary>
+    ///     Captures all additional unmapped properties from the JSON payload.
+    ///     This is used internally to store extension data including SIP headers.
+    /// </summary>
+    [System.Text.Json.Serialization.JsonExtensionData]
+    [Newtonsoft.Json.JsonExtensionData]
+
+    // ReSharper disable once CollectionNeverUpdated.Global
+    public Dictionary<string, object> ExtensionData { get; set; } = new Dictionary<string, object>();
+
+    /// <summary>
+    ///     Gets all SIP header properties (properties starting with "SipHeader_X-") from the webhook payload.
+    ///     The dictionary key is the full property name (e.g., "SipHeader_X-Custom") and the value is the header value.
+    /// </summary>
+    [System.Text.Json.Serialization.JsonIgnore]
+    [Newtonsoft.Json.JsonIgnore]
+    public Dictionary<string, string> SipHeaders =>
+        this.ExtensionData
+            .Where(kvp => kvp.Key.StartsWith("SipHeader_X-"))
+            .ToDictionary(kvp => kvp.Key, kvp => GetStringValue(kvp.Value));
+
+    private static string GetStringValue(object value) =>
+        value switch
+        {
+            JsonElement jsonElement => jsonElement.GetString(),
+            JToken jToken => jToken.Value<string>(),
+            string str => str,
+            _ => value?.ToString(),
+        };
 }