Added custom headers to webhooks

src/SparkPost.Tests/DataMapperTests.cs

@@ -884,6 +884,22 @@ public void Target()
                 dataMapper.ToDictionary(webhook)["target"].ShouldEqual(webhook.Target);
             }
 
+            [Test]
+            public void CustomHeaders()
+            {
+                var webhook = new Webhook
+                {
+                    CustomHeaders = new
+                    {
+                        XAPIKey = "abcd"
+                    }
+                };
+
+                var dictionary = dataMapper.ToDictionary(webhook);
+                var customHeadersDetails = dictionary["custom_headers"].CastAs<IDictionary<string, object>>();
+                customHeadersDetails["x-api-key"].ShouldEqual("abcd");
+            }
+
             [Test]
             public void AuthType()
             {

src/SparkPost/ListWebhookResponse.cs

@@ -31,6 +31,7 @@ internal static Webhook ConvertToAWebhook(dynamic r)
                 Id = r.id,
                 Name = r.name,
                 Target = r.target,
+                CustomHeaders = r.custom_headers,
                 Events = events,
                 AuthType = r.auth_type,
                 AuthRequestDetails = r.auth_request_details,

src/SparkPost/Webhook.cs

@@ -13,6 +13,7 @@ public Webhook()
         public string Id { get; set; }
         public string Name { get; set; }
         public string Target { get; set; }
+        public object CustomHeaders { get; set; }
         public IList<string> Events { get; set; }
 
         public DateTime? LastSuccessful { get; set; }